The first step in an incident response plan is typically preparation12. However, among the options provided, validating the incident would be the first step. This involves confirming that a security event is actually an incident3. It's important to verify the event to avoid wasting resources on false positives.
References:
Incident Response Plan: Frameworks and Steps - CrowdStrike
What is Incident Response? Plan and Steps | Microsoft Security
What Are the Phases of an Incident Response Plan? - ISC2 Blog

The best indicator of whether a PIR performed by the PMO was effective is whether project outcomes have been realized. Project outcomes are the benefits or value that a project delivers to its stakeholders, such as improved efficiency, quality, customer satisfaction, or revenue. A PIR should evaluate whether project outcomes have been achieved in accordance with project objectives, scope, budget, and schedule. The other options are not as good as project outcomes in determining the effectiveness of a PIR. Lessons learned are valuable inputs for improving future projects, but they do not measure whether project outcomes have been realized. Management approval of the PIR report is a sign of acceptance and support for the PIR findings and recommendations, but it does not reflect whether project outcomes have been achieved. The review performed by an external provider is a way of ensuring objectivity and independence for the PIR, but it does not guarantee whether project outcomes have been realized. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.3

The most significant risk when an application uses individual end-user accounts to access the underlying database is that users may be able to circumvent application controls. Application controls are the policies, procedures, and mechanisms that ensure the accuracy, completeness, validity, and authorization of transactions and data within an application. Application controls can include input validation, output verification, processing logic, reconciliation, exception handling, and audit trails. Application controls can help prevent or detect errors, fraud, or unauthorized access or modification of data.
However, if an application uses individual end-user accounts to access the underlying database, it means that the users have direct access to the database without going through the application layer. This can expose the database to potential risks such as:
Users may be able to bypass the application controls and manipulate the data in the database directly using SQL commands or other tools. For example, users may be able to change their own or others' salaries, grades, or balances without proper authorization or validation.
Users may be able to access or disclose sensitive or confidential data that they are not supposed to see or share. For example, users may be able to view other users' personal information, passwords, or credit card numbers.
Users may be able to introduce errors or inconsistencies in the data by entering invalid or incorrect data or by deleting or modifying existing data. For example, users may be able to create duplicate records, break referential integrity, or cause data loss or corruption.
Users may be able to compromise the security and performance of the database by creating unauthorized objects, granting excessive privileges, executing malicious code, or consuming excessive resources. For example, users may be able to create backdoors, viruses, or denial-of-service attacks.
Therefore, using individual end-user accounts to access the underlying database can pose a serious threat to the integrity, confidentiality, availability, and reliability of the data and the application.
The other options are not as significant as option C. Multiple connects to the database are used and slow the process is a performance issue that can affect the efficiency and responsiveness of the application and the database, but it does not necessarily compromise the data quality or security. User accounts may remain active after a termination is a security issue that can increase the risk of unauthorized access or misuse of data by former employees or others who have access to their credentials, but it can be mitigated by implementing proper account management and monitoring processes. Application may not capture a complete audit trail is a compliance issue that can affect the accountability and traceability of transactions and data within the application and the database, but it does not directly affect the data accuracy or protection.
References:
Should application users be database users? - Stack Overflow1
An Approach Toward Sarbanes-Oxley ITGC Risk Assessment - ISACA2
ISACA CISA Certified Information Systems Auditor Exam ... - PUPUWEB3
Why inactive accounts are a security risk | Stratosphere4

This is because audit trails are records of system activity and user actions that can provide evidence of the validity and integrity of transactions and data in a financial application system. Audit trails can help to ensure compliance with laws, regulations, policies, and standards, as well as to detect and prevent fraud, errors, or misuse of information. Audit trails can also facilitate auditing, monitoring, and evaluation of the financial application system's performance and controls1.
The application should meet the organization's requirements (A) is not the best answer, because it is a general and obvious criterion that applies to any application system acquisition, not a specific and important recommendation for a financial application system. The organization's requirementsshould be clearly defined and documented in the RFP, but they may not necessarily include audit trails as a design feature.
Potential suppliers should have experience in the relevant area is not the best answer, because it is a factor that affects the selection of the supplier, not the design of the financial application system. The experience and reputation of potential suppliers should be evaluated and verified during the RFP process, but they may not guarantee that the supplier will include audit trails in the design.
Vendor employee background checks should be conducted regularly (D) is not the best answer, because it is a measure that affects the security and trustworthiness of the vendor, not the design of the financial application system. Vendor employee background checks should be performed as part of the vendor management and due diligence process, but they may not ensure that the vendor will include audit trails in the design.