BOTH INTERNATIONAL & INLAND Which is TRUE of the signal consisting of five or more short blasts on the ship's whistle?

Correct Answer: Option A — It indicates doubt as to the other vessel's action

Rule 34(d) states that when vessels in sight of one another fail to understand the intentions or actions of the other, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. This is the mandatory danger signal.