The best phase of the software development life cycle to initiate the discussion of application controls is the application design phase when process functionalities are finalized. Application controls are the policies, procedures, and techniques that ensure the completeness, accuracy, validity, and authorization of data input, processing, output, and storage in an application. Application controls help prevent, detect, or correct errors and fraud in software applications. Examples of application controls include input validation, edit checks, reconciliation, encryption, access control, audit trails, etc.
The application design phase is when the software requirements are translated into a logical and physical design that specifies how the application will look and work. This phase is the best time to discuss application controls because it allows the developers to incorporate them into the design specifications and ensure that they are aligned with the business objectives and user needs. By discussing application controls early in the design phase, the developers can also avoid costly rework or changes later in the development process.
The other phases are not as optimal as the application design phase to initiate the discussion of application controls. A. Business case development phase when stakeholders are identified. The business case development phase is when the feasibility, scope, objectives, benefits, risks, and costs of a software project are defined and evaluated. This phase is important for obtaining stakeholder approval and support for the project, but it is too early to discuss application controls in detail because the software requirements and functionalities are not yet clear or finalized. B. User acceptance testing (UAT) phase when test scenarios are designed. The user acceptance testing phase is when the software is tested by the end-users or stakeholders to verify that it meets their expectations and requirements. This phase is too late to discuss application controls because it is near the end of the development process and any changes or additions to the application controls would require retesting and revalidation of the software. C. Application coding phase when algorithms are developed to solve business problems. The application coding phase is when the software design is translated into executable code using programming languages and tools. This phase is not ideal to discuss application controls because it is after the design phase and any changes or additions to the application controls would require redesigning and recoding of the software.
References:
* ISACA, CISA Review Manual, 27th Edition, 2019, p. 2471
* ISACA, CISA Review Questions, Answers & Explanations Database - 12 Month Subscription2
* What Is Application Control? | McAfee3
* What Is Application Lifecycle Management? | Red Hat4

The auditor implemented a specific control during the development of the system. This would impair the auditor's independence, as it would create a self-review threat, which is a situation where an auditor has to evaluate or review the results of his or her own work or judgment1. A self-review threat may compromise the auditor's objectivity and impartiality, as the auditor may be biased or influenced by his or her own involvement or interest in the system1. The auditor may also face a conflict of interest or a loss of credibility if he or she has to report on any issues or deficiencies related to the control he or she implemented.

The most important thing for an IS auditor to verify when reviewing the use of an outsourcer for disposal of storage media is that the vendor's process appropriately sanitizes the media before disposal. As explained in the previous question, storage media may contain sensitive or confidential information that needs to be protected from unauthorized access, disclosure, or misuse. The IS auditor should verify that the vendor has a process that appropriately sanitizes the media before disposal, such as wiping, degaussing, shredding, or incinerating, and that the process is effective and compliant with the organization's policies and standards. The other options are not as important as verifying the vendor's process, because they either do not ensure the security and privacy of the information on the media, or they aresecondary to the vendor's process. References: CISA Review Manual (Digital Version)1, Chapter 5, Section 5.2.7

Evidence collection is the process of identifying, acquiring, preserving, and documenting digital evidence from various sources, such as computers, networks, mobile devices, or cloud services, that can be used to support the investigation and prosecution of cybercrimes. Evidence collection is an IS auditor's primary focus when evaluating the response process for cybercrimes, because it determines the quality and validity of the evidence that can be used to prove or disprove the facts of the case, identify the perpetrators, and recover the losses. Evidence collection should follow the standards and best practices for digital forensics, such as ISO
/IEC 270371, which provide guidelines for ensuring the integrity, authenticity, reliability, and admissibility of the evidence2.
The other possible options are:
* A. Communication with law enforcement: This is the process of reporting, cooperating, and coordinating with law enforcement agencies that have the jurisdiction and authority to investigate and prosecute cybercrimes. Communication with law enforcement is an important aspect of the response process for cybercrimes, but it is not an IS auditor's primary focus when evaluating it. Communication with law enforcement depends on the legal and regulatory requirements, the nature and severity of the incident, and the organizational policies and procedures. Communication with law enforcement should be done after evidence collection, to avoid compromising or contaminating the evidence3.
* B. Notification to regulators: This is the process of informing and updating the relevant regulatory bodies or authorities that oversee or supervise the organization's activities or industry sector about the cybercrime incident. Notification to regulators is an important aspect of the response process for cybercrimes, but it is not an IS auditor's primary focus when evaluating it. Notification to regulators depends on the legal and regulatory requirements, the nature and impact of the incident, and the organizational policies and procedures. Notification to regulators should be doneafter evidence collection, to avoid disclosing sensitiveor confidential information4.
* C. Root cause analysis: This is the process of identifying and analyzing the underlying factors or causes that led to or contributed to the cybercrime incident. Root cause analysis is an important aspect of the response process for cybercrimes, but it is not an IS auditor's primary focus when evaluating it. Root cause analysis helps to prevent or mitigate future incidents, improve security controls and processes, and learn from mistakes. Root cause analysis should be done after evidence collection, to avoid interfering with or affecting theinvestigation5.

A compliance gap analysis is a detailed review of an organization's current state of compliance against a specific regulation or standard. It helps identify the areas and controls that are not meeting the requirements, assess their risk levels, and determine the corrective actions that can be taken to achieve compliance12. A compliance gap analysis is the most useful tool for an IS auditor to review when auditing against a new regulation, as it provides a clear and comprehensive picture of the compliance status, gaps, and remediation plan of the organization.
References
1: Information Security Architecture: Gap Assessment and Prioritization - ISACA
2: How to perform Compliance Gap Analysis? - Sprinto