You are on a semisubmersible being towed and are concerned that a fishing vessel is not taking sufficient action to avoid you. To signal your concern, you should __________.

Correct Answer: Option D — sound five or more short blasts on the whistle

Under Rule 34(d) of the International and Inland Navigation Rules, when vessels in sight are approaching each other and either fails to understand the intentions or actions of the other, the doubtful vessel must indicate immediate doubt by sounding at least five short and rapid blasts on the whistle.