The board of directors has the ultimate responsibility for implementing the organization's governance system.
This includes overseeing the strategic direction and accountability mechanisms that align with good governance practices. The board ensures that governance structures and principles are clearly defined and effectively implemented, providing oversight to management activities. References: Corporate governance principles and guidelines, which often highlight the role of the board in setting and maintaining effective governance systems.

An internal auditor exercises due professional care by enhancing knowledge, skills, and other competencies through ongoing professional development. This action is essential to maintain the necessary proficiency and competency in performing audit tasks, thereby ensuring the quality and effectiveness of the audit work aligns with professional standards and meets the evolving needs of the organization.
Institute of Internal Auditors (IIA) - International Professional Practices Framework (IPPF)

The Internal Audit Activity's Quality Assurance and Improvement Program (QAIP) aims to ensure that the internal audit activities are carried out to the highest standards of quality and comply with the defined audit standards and practices. Sharing the results of the QAIP with the organization's external auditors is permissible and can enhance the understanding and reliance on audit processes. It aids in external audit planning and may contribute to more effective and streamlined audit practices across both internal and external teams.
Institute of Internal Auditors (IIA) - International Professional Practices Framework (IPPF)

Risk appetite is the amount and type of risk that an organization is willing to accept in pursuit of its objectives2. It reflects the organization's risk culture and strategy, and guides the risk assessment, response, and reporting processes3. In this case, the decision to invest in a stock that could have a high expected return rate without taking any risk mitigation activities illustrates a high risk appetite, as the organization is willing to accept a high level of uncertainty and volatility for a potential reward4.
References:
1: Risk Resources in Internal Audit | The IIA
2: Risk-based internal audit - Wikipedia
3: What is Risk Management in Internal Audit - ESG | The Report
4: Internal Audit 1 January 13, 2012 - vsu.edu