The piston cooling system may employ similar components, except that a drain tank is used

The piston cooling system may employ similar components, except that a drain tank is used instead of a head tankThat means this system _____.

A.doesnt use a drain tank but a head tank

B.uses a drain tank not head tank

C.uses a drain tank and a head tank

D.uses neither a drain tank nor a head tank

请帮忙给出正确答案和分析，谢谢！