INLAND ONLY One and two short blast signals must be sounded on inland waters when __________.

Correct Answer: Option A — two power-driven vessel are in sight of one another and are meeting within a half mile

Under Inland Navigation Rules, for the condition where 'One and two short blast signals must be sounded on inland waters when', the correct requirement is: 'Two power-driven vessel are in sight of one another and are meeting at a distance of one half mile'. This standard ensures clear navigational intent and collision avoidance.