What is the purpose of a relief valve？A.to fill 2 tanks at the same timeB.to use pump at a

What is the purpose of a relief valve？

A.to fill 2 tanks at the same time

B.to use pump at a higher pressure

C.to return liquid to suction side if discharge valve is closed

D.All of the above are true

请帮忙给出正确答案和分析，谢谢！