417 BOTH INTERNATIONAL & INLAND While underway and in sight of another vessel crossing less than .5 mile away, you put your engines full speed astern. Which statement concerning whistle signals is TRUE?

A. You must sound three short blasts on the whistle.
B. You must sound one blast if backing to starboard.
C. You must sound whistle signals only if the vessels are meeting.
D. You need not sound any whistle signals.