Marina Exam: Your vessel is backing out of a slip in a harbor. Visibility is restricted. You should sound __________.

Your vessel is backing out of a slip in a harbor. Visibility is restricted. You should sound __________.

A.one long blast only 
B.the danger signal 
C.one prolonged blast followed by three short blasts when leaving the slip 
D.one prolonged blast only 

Answer: 



D.one prolonged blast only