When does a pilot vessel exhibit her identity lights?

A pilot vessel exhibits her identity lights whenever she is on pilotage duty to clearly indicate her role and status to other vessels. This is essential for safety navigation and communication in maritime traffic, as it informs other ships that the pilot vessel is actively engaged in assisting with piloting operations.

Distinctive identity lights help ensure other mariners recognize the vessel's purpose and can take appropriate measures. The regulations under COLREGs specify that these lights must be displayed anytime the vessel is on duty, which includes both day and night conditions, making option C the correct choice.

Options that suggest the vessel exhibits these lights only at specific times, such as only at night or only when anchored, do not align with the rules governing the visibility of identity lights, as they must be consistently displayed during piloting activities, regardless of the time of day or the vessel's position.