Aligning IT strategy with business strategy primarily helps an organization to optimize investments in IT. This is because alignment ensures that IT resources and capabilities are aligned with the business goals and priorities, and that IT delivers value to the business in terms of efficiency, effectiveness, innovation, and competitive advantage12. By aligning IT strategy with business strategy, an organization can avoid wasting money and time on IT projects or services that do not support or contribute to the business outcomes3. Alignment also helps to identify and prioritize the most critical and valuable IT initiatives that can create or optimize business value4.
Therefore, the correct answer to your question is A. optimize investments in IT.

The finding that should be of most concern to an IS auditor when evaluating information security governance within an organization is that the data center manager has final sign-off on security projects. This indicates a lack of segregation of duties and a potential conflict of interest between the operational and security roles. The data center manager may have access to sensitive information or systems that should be protected by security controls, or may influence or override security decisions that are not in the best interest of the organization.
This finding also suggests that there is no clear accountability or authority for information security governance at a higher level, such as senior management or board of directors. The other findings are not as concerning as this one, although they may indicate some areas for improvement or monitoring. References:
* ISACA, CISA Review Manual, 27th Edition, chapter 5, section 5.11
* ISACA, IT Governance Using COBIT and Val IT: Student Booklet - 2nd Edition4

A differential backup scheme is the best option when storage media is limited, as it only backs up the data that has changed since the last full backup. This reduces the amount of storage space required and also simplifies the restoration process, as only the last full backup and the last differential backup are needed. A real-time backup scheme would require continuous replication of data, which would consume a lot of storage space and network bandwidth. A virtual backup scheme would create a snapshot of the data at a point in time, but it would not reduce the storage space required, as it would still need to store the changes made to the data.
A full backup scheme would back up all the data every time, which would require the most storage space and also take longer to complete. References: ISACA, CISA Review Manual, 27th Edition, 2018, page 405

The most effective way to detect an intrusion attempt is to periodically review log files, which record the activities and events on a system or network. Log files can provide evidence of unauthorized access attempts, malicious activities, or system errors. Configuring the router as a firewall, using smart cards with one-time passwords, and installing biometrics-based authentication are preventive controls that can reduce the likelihood of an intrusion, but they do not detect it. References: ISACA CISA Review Manual 27th Edition, page 301

The most critical finding for an IS auditor following up on a recent security incident is that the security weakness facilitating the attack was not identified. This finding indicates that the root cause of the incident was not analyzed, and the vulnerability that allowed the attack to succeed was not remediated. This means that the organization is still exposed to the same or similar attacks in the future, and its security posture has not improved. Identifying and addressing the security weakness is a key step in the incident response process, as it helps to prevent recurrence, mitigate impact, and improve resilience.
The other findings are not as critical as the failure to identify the security weakness, but they are still important issues that should be addressed by the organization. The attack was not automatically blocked by the intrusion detection system (IDS) is a finding that suggests that the IDS was not configured properly, or that it did not have the latest signatures or rules to detect and prevent the attack. The attack could not be traced back to the originating person is a finding that implies that the organization did not have sufficient logging, monitoring, or forensic capabilities to identify and attribute the attacker. Appropriate response documentation was not maintained is a finding that indicates that the organization did not follow a consistent and formal incident response procedure, or that it did not document its actions, decisions, and lessons learned from the incident.
References:
* ISACA CISA Review Manual 27th Edition (2019), page 254
* Incident Response Process - ISACA1
* Incident Response: How to Identify and Fix Security Weaknesses