BOTH INTERNATIONAL & INLAND Which statement is TRUE concerning the light used with whistle signals?

Correct Answer: Option C — Its purpose is to supplement short blasts of the whistle.

Under Inland Navigation Rules, for the condition where 'Which statement is TRUE concerning the light used with whistle signals', the correct requirement is: 'It is only used to supplement short blasts of the whistle.'. This standard ensures clear navigational intent and collision avoidance.