The best way to support risk-based decisions by senior management would be to map findings to objectives, because this would help them understand how the identified risks affect the achievement of the organization's goals and priorities. Mapping findings to objectives would also help senior management evaluate the trade-offs between different risk responses and allocate resources accordingly. By linking risks to objectives, the risk practitioner can communicate the value and impact of risk management in a clear and relevant way.
References = Risk IT Framework, ISACA, 2022, p. 17

The scenario that is most important to communicate to senior management is the accepted risk scenarios with impact exceeding the risk tolerance, as it indicates a significant risk issue or breach that may affect the achievement of the organizational objectives, and may require a review or escalation action. The other options are not the most important scenarios, as they may not indicate a risk issue or breach, but rather a risk monitoring, sharing, or management activity, respectively, that may not affect the organizational objectives directly or significantly. References = CRISC Review Manual, 7th Edition, page 109.

According to the CRISC Review Manual1, a third-party audit is an independent and objective examination of an organization's security controls by an external auditor or organization. A third-party audit provides the most objective assessment of the effectiveness of an organization's security controls, as it helps to avoid any conflicts of interest, biases, or assumptions that may affect the internal audit, review, or testing. A third-party audit also helps to ensure that the security controls comply with the relevant standards, regulations, and best practices, and that they meet the expectations and requirements of the stakeholders, such as customers, partners, or regulators. References = CRISC Review Manual1, page 224.