In a consulting engagement, the internal auditors collaborate with management to determine the objectives and scope. In contrast, for assurance engagements, the internal audit activity sets the objectives and scope independently to provide an unbiased assessment. References:
* IIA Standard 2010: Planning.
* IIA Practice Guide: Consulting Services.

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.

While the internal audit may be involved in assessing the adequacy of the organization's efforts in corporate social responsibility (CSR), the primary responsibility for ongoing monitoring of CSR activities, such as reducing carbon footprint, typically rests with operational management. In this context, the Facility Operation Manager would be the most appropriate choice, as they are directly involved in managing the day-to-day operations that affect the organization's environmental impact.
General industry practices on CSR responsibilities

Due professional care is the care and skill expected of a reasonably prudent and competent internal auditor. It requires internal auditors to follow the IPPF. One of the aspects of due professional care is to perform risk-based audits, which means identifying and assessing the risks that may affect the organization's objectives, and designing and executing audit procedures that provide reasonable assurance on the effectiveness of risk management and internal control. Therefore, option B is an appropriate statement.

In this situation, the appropriate action for the internal auditor is to remain independent and avoid roles that could impair this independence, such as making managerial decisions. By advising and then directing the management to submit the proposal to senior management and the board, the auditor maintains an advisory role without crossing into decision-making territory, thus preserving the independence necessary for an assurance role.
Institute of Internal Auditors (IIA) - International Standards for the Professional Practice of Internal Auditing