According to the International Standards for the Professional Practice of Internal Auditing (Standards), internal auditors must exhibit due professional care in their work. Due professional care implies that internal auditors must apply the care and skill expected of a reasonably prudent and competent auditor. Standard 1220 of the IIA's International Standards states that internal auditors must consider the use of technology-based audit and other data analysis techniques. Furthermore, they should be alert to the significant risks that might affect objectives, operations, or resources. Demonstrating the necessary skills and proficiency (Option B) directly aligns with the requirement of due professional care, as it ensures that auditors have the capability to identify and manage risks effectively.
IIA Standards, Standard 1220: Due Professional Care
IIA's International Professional Practices Framework (IPPF)

The scenario described involves a self-review threat, which arises when auditors review work that they previously performed or were involved in. In this case, since the CAE had initially established and managed the risk management function before a chief risk officer took over, engaging an external resource to audit this function mitigates the threat to objectivity by ensuring an independent review. This action avoids potential bias and maintains the integrity of the audit process.
IIA guidance on objectivity and conflicts of interest.

The risk created when a manager bypasses organizational policies and procedures to meet an organization's objective is best described as monitoring failure risk. This type of risk arises when there is insufficient oversight or ineffective controls that fail to detect or prevent departures from prescribed procedures, which could lead to non-compliance, inefficiencies, or other adverse outcomes.
IIA guidance on risk categories and management control frameworks.

When a risk assessment shows that the cost of addressing a particular risk is greater than the perceived benefit, the appropriate risk response approach is to accept the risk. Risk acceptance means acknowledging that the risk exists but deciding not to take any action to mitigate it, usually because the cost of mitigation is higher than the potential impact. This approach is a rational decision when the risk is deemed to have a low likelihood or impact, or when other controls are considered sufficient.
The IIA Standards: Standard 2120 - Risk Management: "The internal audit activity must evaluate the effectiveness and contribute to the improvement of risk management processes." COSO ERM Framework: Discusses risk response options including risk acceptance as a viable strategy when the cost-benefit analysis justifies it.

If there are unresolved scope restrictions, the chief audit executive (CAE) should consider whether to pursue the audit and note the scope restrictions in the audit report. This is important because scope restrictions can limit the audit's ability to fully assess the control environment, and documenting these limitations helps ensure that the audit report reflects the extent to which the auditor was able to evaluate the control environment.
The IIA's International Standards for the Professional Practice of Internal Auditing regarding scope limitations and reporting.