下列清热凉血药中，能清泻肝火的药物是（）

A.牡丹皮

B.赤芍

C.玄参

D.水牛角

E.生地

A group of 7 fishermen chartered a boat for a day to fish for flounder. The boat costs x dollars per day to rent. If the group can find 3 more fishermen on the docks who are willing to come aboard and share the rental costs, how much less will the rental cost be per person in terms of x ？（）

A. x/70

B. x/35

C. 3x/70

D. 3x/10

E. 3x/7