What is NOT a distress signal?（）

A.A continuous sounding of the fog horn
B.Firing a gun every minute
C.Five or more short rapid blasts on the whistle
D.A square flag and ball flown from the mast

A.forty two months from the date of manufacture
B.thirty six months from the date of the last inspection
C.twenty four months from the date of approval
D.twelve months from the date of purchase

A.that a distress message will follow
B.a request for assistance in searching for a man overboard
C.an urgent warning about a cyclone
D.All of the above