If a vessel is sagging，what kind of stress is placed on the sheer strake?（）

A.floors
B.intercostals
C.stringers
D.tank top supports

A.frames to which the tank top and bottom shell are fastened on a double bottomed ship
B.transverse members of the ships frame which support the decks
C.longitudinal beams in the extreme bottom of a ship from which the ship's ribs start
D.longitudinal angle bars fastened to a surface for strength

A.also called decks
B.vertical transverse plates connecting the vertical keel with the margin plates
C.large beams fitted in various parts of the vessel for additional strength
D.found in passenger and berthing spaces only