The material used extensively as electrolytic protection around bronze propellers is（）.

A.to avoid the rearrangement of the cargo loaded on board
B.to ensure the safety of the ship and cargo
C.to reject the damaged cargo during loading operation
D.to prevent the spontaneous combustion of coal and grain

A.to ensure the safety of the ship and protect the cargo from being damaged
B.to avoid the rearrangement of the cargo loaded on board
C.to reject the damaged cargo during loading
D.to prevent the spontaneous combustion of coal and grain