Incidents involving modern key must be reported to whom?

The correct choice emphasizes the importance of reporting incidents involving modern key to multiple relevant authorities, which is crucial for maintaining the integrity and security of communication systems. Reporting to both the Command Authority and the Validation Authority ensures that all levels of leadership are informed and can take the necessary actions to mitigate risk and prevent further incidents. The Command Authority is responsible for overarching command decisions, while the Validation Authority may be tasked with verifying the incident's details and assessing its impact on operational security.

Involving all these parties allows for a comprehensive response to incidents, ensuring that there are no gaps in information flow and that each authority can fulfill its respective role effectively. This approach fosters a culture of security and accountability, ensuring that all necessary protocols are followed and that the response to any key-related incident is swift and coordinated.