The most important control to assess in an audit of an organization's accounts payable processes is segregation of duties between issuing purchase orders and making payments. Segregation of duties is a principle that requires different individuals or departments to perform different tasks or functions within a process, in order to prevent fraud, errors, or conflicts of interest. In the accounts payable process, segregation of duties between issuing purchase orders and making payments ensures that no one person can initiate and complete a transaction without proper authorization and verification. This reduces the risk of duplicate payments, overpayments, unauthorized payments, or payments to fictitious vendors.
References:
* Accounts payable controls
* Accounts Payable Internal Controls: A Simple Checklist

The best way to enforce the principle of least privilege on a server containing data with different security classifications is to apply access controls determined by the data owner. The principle of least privilege states that users should only have the minimum level of access required to perform their tasks. The data owner is the person who has the authority and responsibility to classify, label, and protect the data according to its sensitivity and value. The data owner can define the access rightsand permissions for each user or role based on the data classification policy and the business needs. This will ensure that only authorized and appropriate users can access the data and prevent unauthorized or excessive access that could compromise the confidentiality, integrity, or availability of the data. References:
* CISA Review Manual (Digital Version)
* CISA Questions, Answers & Explanations Database

The impact if corrective actions are not taken is the most important factor to consider when scheduling follow- up audits. An IS auditor should prioritize the follow-up audits based on the risk and potential consequences of not addressing the audit findings and recommendations. The other options are less important factors that may affect the timing and scope of the follow-up audits, but not their necessity or urgency. References:
* CISA Review Manual(Digital Version), Chapter 2, Section 2.5.31
* CISA Review Questions, Answers & Explanations Database, Question ID 207

A biometric access device installed at the entrance to a facility is a type of preventive control. Preventive controls are designed to deter or prevent undesirable events from occurring12. They are proactive measures that aim to inhibit incidents before they happen12. In this case, the biometric access device prevents unauthorized individuals from gaining access to the facility by requiring unique biological characteristics for authentication12.
References:
Guide to Biometric Access Control & Door Lock Security - Avigilon
Biometric access control: meaning, types and implementation - Smowl

Shadow IT often arises when approved software does not meet user requirements (Option D), leading employees to seek alternative solutions.
ISACA CISA Reference: IT governance frameworks stress the need for user-centric IT policies to mitigate shadow IT risks.
Risk Implication: Shadow IT introduces security vulnerabilities, compliance risks, and potential data breaches.