The best way to determine whether a test of a disaster recovery plan (DRP) was successful is to analyze whether predetermined test objectives were met. Test objectives are specific, measurable, achievable, relevant, and time-bound (SMART) goals that define what the test aims to accomplish and how it will be evaluated. Test objectives should be aligned with the DRP objectives and scope, and should cover aspects such as recovery time objectives (RTOs), recovery point objectives (RPOs), critical business functions, roles and responsibilities, communication channels, backup systems, and contingency procedures. By comparing the actual test results with the expected test objectives, the IS auditor can measure the effectiveness and efficiency of the DRP and identify any gaps or weaknesses that need to be addressed.

The best way to reduce the immediate risk associated with using an unsupported version of the software is to segregate the outdated software system from the main network. This will limit the exposure of the system to potential attacks and prevent it from compromising other systems on the network. Segregating the system will also reduce the impact of any security incidents that may occur on the system.
Monitoring network traffic attempting to reach the outdated software system (option C) is not the best way to reduce the risk, as it will not prevent or stop any attacks on the system. It will only provide visibility into the network activity and alert the auditee of any suspicious or malicious traffic.
Verifying all patches have been applied to the software system's outdated version (option A) and closing all unused ports on the outdated software system (option B) are also not the best ways to reduce the risk, as they will not address the underlying issue of using an unsupported version of the software. Patches and ports may still have vulnerabilities that are not fixed by the vendor, and attackers may exploit them to gain access to the system.
Therefore, option D is the correct answer.
References:
* Introduction (Part 1 of 7: Mitigating Risks of Unsupported Operating Systems)
* Summary (Part 7of 7: Mitigating Risks of Unsupported Operating Systems)
* Upgrade, Retire, or Replace Unsupported Software (Part 4 of 7: Mitigating Risks of Unsupported Operating Systems)

The strategy that would provide the greatest assurance of system quality at implementation is delivering only the core functionality on the initial target date. This strategy can help avoid compromising the quality of the system by focusing on the essential features that meet the user needs and expectations. Delivering only the core functionality can also help reduce the scope creep, complexity, and testing efforts of the system development project.
Implementing overtime pay and bonuses for all development staff, utilizing new system development tools to improve productivity, and recruiting IS staff to expedite system development are not strategies that would provide the greatest assurance of system quality at implementation. These strategies may help speed up the system development process, but they may also introduce new risks or challenges such as burnout, learning curve, integration issues, or communication gaps. These risks or challenges may adversely affect the quality of the system.