BOTH INTERNATIONAL & INLAND If you hear the firing of a gun at one minute intervals from another vessel, this indicates that __________.

Correct Answer: Option D — the vessel is in distress

Under Inland Navigation Rules, for the condition where 'If you hear the firing of a gun at one minute intervals from another vessel, this indicates that', the correct requirement is: 'the vessel is in distress'. This standard ensures clear navigational intent and collision avoidance.