In astern towing，a tow span，also called the tow bar or towing arch，is used to（）.

A. insure that the hawser leads directly aft as it passes over the stern of the towing vessel
B. increase the stability of the towing vessel by raising the hawser off the deck
C. reduce chafing of the towing hawser
D. prevent fouling of the hawser on deck gear located on the stern of the towing vessel