A rigid lifesaving device designed to support survivors in the water is a（）.

A.should be righted by standing on the carbon dioxide cylinder，holding the righting straps，and leaning backwards
B.should be righted by standing on the life line，holding the righting straps，and leaning backwards
C.will right itself when the canopy tubes inflate
D.must be cleared of the buoyant equipment before it will right itself

A.at the bow
B.at the stern
C.in the middle
D.all around