The exact definition of the service levels and their measurement is the first thing that the IS auditor should review in order to understand the problem of different opinions on the availability of their application servers.
Service levels are the agreed-upon standards or targets for delivering IT services, such as availability, reliability, performance, and security. Service level measurement is the process ofcollecting, analyzing, and reporting data related to the achievement of service levels. By reviewing the exact definition of the service levels and their measurement, the IS auditor can identify any gaps, inconsistencies, or ambiguities that may cause confusion or disagreement among IT and the business. The other options are not as important as reviewing the exact definition of the service levels and their measurement, as they do not address the root cause of the problem. References: CISA Review Manual, 27th Edition,page 372

Write access to production program libraries presents the greatest risk when granted to a new member of the system development staff. Production program libraries contain executable code that runs on live systems and supports critical business functions. Write access allows a user to modify or delete existing programs, or add new programs to the library. If a user were to make unauthorized or erroneous changes to production programs, it could cause serious disruptions, errors, or security breaches in the organization's operations.
Therefore, write access to production program libraries should be restricted to authorized personnel only, and subject to strict change management controls.

When reviewing an enterprise architecture (EA) department's decision to change a legacy system's components while maintaining its original functionality, an IS auditor should understand the current business capabilities delivered by the legacy system, as this would help to evaluate whether the change is justified, feasible, and aligned with the business goals and needs. The proposed network topology to be used by the redesigned system, the data flows between the components to be used by the redesigned system, and the database entity relationships within the legacy system are technical details that are less relevant for an IS auditor to understand when reviewing this decision. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.2

This control is best implemented through system configuration because it can be enforced automatically by setting a parameter in the network operating system or directory service. This ensures that temporary workers do not have access to the network beyond their authorized period, and reduces the risk ofunauthorized or malicious use of their accounts12.
References1: Configuration and Change Management - CISA2: What is IT Governance? - Definition from Techopedia

The most important process to help ensure the application provides accurate calculations is quality assurance (QA), which involves verifying that the application meets the specified requirements and standards, and testing the application for functionality, performance, reliability, security, and usability. QA helps to identify and correct any defects or errors in the application before it is deployed to the production environment. Key performance indicator (KPI) monitoring, change management, and configuration management are important processes for managing and maintaining the application after it is implemented, but they do not directly ensure the accuracy of the calculations performed by the application. References: CISA Review Manual (Digital Version), Chapter 3: Information Systems Acquisition, Development & Implementation, Section 3.3:
Practices for Quality Assurance