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

The IS auditor's independence would be most likely impaired if they implemented a specific control during the development of an application system. This is because the IS auditor would be auditing their own work, which creates a self-review threat that could compromise their objectivity and impartiality. The IS auditor should avoid participating in any operational or management activities that could affect their ability to perform an unbiased audit. The other options do not pose a significant threat to the IS auditor's independence, as long as they follow the ethical standards and guidelines of the profession.

The most helpful thing for an IS auditor to review when evaluating an organization's business processes that are supported by applications and IT systems is the enterprise architecture (EA). EA is the practice of designing a business with a holistic view, considering all of its parts and how they interact. EA defines the overall goals, the strategies that support those goals, and the tactics that are needed to execute those strategies.
EA also outlines the ways various components of IT projects interact with one another and with the business processes. By reviewing the EA, an IS auditor can gain a comprehensive understanding of how the organization aligns its IT efforts with its overall mission, business strategy, and priorities. An IS auditor can also assess the effectiveness, efficiency, agility, and continuity of complex business operations.
The other options are not as helpful as option B. A configuration management database (CMDB) is a database that stores and manages information about the components that make up an IT system. A CMDB tracks individual configuration items (CIs), such as hardware, software, or data assets, and their attributes, dependencies, and changes over time. A CMDB can help an IS auditor to monitor the performance, availability, and configuration of IT assets, but it does not provide a holistic view of how they support the business processes. IT portfolio management is the practice of managing IT investments, projects, and activities as a portfolio. IT portfolio management aims to optimize the value, risk, and cost of IT initiatives and align them with the business objectives. IT portfolio management can help an IS auditor to evaluate the return on IT investments and the alignment of IT projects with the business strategy, but it does not provide a detailed view of how they support the business processes. IT service management (ITSM) is the practice of planning, implementing, managing, and optimizing IT services to meet the needs of end users and customers.
ITSM focuses on delivering IT as a service using standardized processes and best practices. ITSM can help an IS auditor to review the quality, efficiency, and effectiveness of IT service delivery and support, but it does not provide a comprehensive view of how they support the business processes. References: What is enterprise architecture (EA)? - RingCentral, What is a configuration management database (CMDB)? - Red Hat, IT Portfolio Management Strategies | Smartsheet, What is IT service management (ITSM)? | IBM

The best way to mitigate the risk associated with unintentional modifications of complex calculations in end- user computing (EUC) is to execute copies of EUC programs out of a secure library. This will ensure that the original EUC programs are protected from unauthorized changes and that thecopies are run in a controlled environment. A secure library is a repository of EUC programs that have been tested, validated, and approved by the appropriate authority. Executing copies of EUC programs out of a secure library can also help with version control, backup, and recovery of EUC programs. Having an independent party review the source calculations, implementing complex password controls, and verifying EUC results through manual calculations are not as effective as executing copies of EUC programs out of a secure library, as they do not prevent or detect unintentional modifications of complex calculations in EUC. References: End-User Computing (EUC) Risks: A Comprehensive Guide, End User Computing (EUC) Risk Management