INLAND ONLY When shall whistle signals be exchanged by power-driven vessels in sight of one another?

Correct Answer: Option D — they are passing within half a mile of each other

Inland Rule 34(a) mandates that power-driven vessels in sight of one another must exchange whistle signals when passing within half a mile of each other. This ensures clear communication of intent in confined waters, regardless of whether a course change is necessary to complete the passing maneuver safely.