INTERNATIONAL ONLY Two power-driven vessels are crossing within one half mile of each other as shown in illustration D042RR below. Vessel "A" sounds one short blast of the whistle. What does this signal mean?

Correct Answer: Option D — None of the above

Under COLREGS Rule 34(a), one short blast signifies an alteration of course to starboard. It is not a proposal for a passing arrangement or an intent to overtake. Because the signal is used incorrectly in this context, it carries no valid meaning under the International Rules of the Road.