Correct Answer: CThe best course of action for the Chief Audit Executive (CAE) when operational management has not addressed an internal control issue that poses a risk of material misstatement of the organization's financial statements is to escalate the issue to senior management. Senior management has the primary responsibility for addressing significant internal control issues and ensuring the integrity of financial reporting. By escalating the issue to senior management, the CAE ensures that the matter is addressed by those who are responsible and can implement the necessary corrective actions. Immediate reporting to the board would be premature without first giving senior management the opportunity to address the issue, and taking corrective action directly would be outside the typical scope of the CAE's responsibilities.