Battens are fitted in cargo holds across the frames of the vessel from the turn of the bilge upward. The purpose of these cargo battens is（）.

A. for securing a snatch block when snaking cargo into the wings of the hold
B. to prevent cargo from coming in contact with the vessel's frames or shell plating
C. to provide fittings to which cargo lashings may be secured
D. to support the dunnage floors which are laid down between tiers of cargo