The board of directors is responsible for the oversight of the organization's governance framework, which includes obtaining assurance on external financial, regulatory, and internal audits. This responsibility is crucial for ensuring the integrity and accuracy of financial reporting and compliance with laws and regulations.
Management, on the other hand, is responsible for operational activities, such as complying with laws, assigning authority, and monitoring performance. References:
* Institute of Internal Auditors (IIA) - Governance and oversight responsibilities.
* IIA's International Professional Practices Framework (IPPF).

The scenario where the chief audit executive (CAE) declines a request to review and provide feedback on strategic plans for a merger due to the team's lack of experience with mergers demonstrates internal audit proficiency. Proficiency in internal auditing involves understanding and applying knowledge, skills, and competencies to perform tasks according to professional standards. Recognizing the limitations of the audit team's expertise and declining engagements that exceed their proficiency safeguards the quality and reliability of the audit function.References: IIA Standard 1210 - Proficiency, which mandates that internal auditors must possess the knowledge, skills, and other competencies needed to perform their individual responsibilities.

When prioritizing fraud risks, the most important factor for internal auditors to consider is the organization's culture. A culture that does not robustly promote ethical behavior or where management overrides controls can significantly increase the likelihood and impact of fraud. This aligns with risk management principles that consider organizational culture as a key element in the effectiveness of controls to prevent, detect, and respond to fraud.References: The Institute of Internal Auditors (IIA) guidance on assessing and managing fraud risks and organizational culture.