—Which of the two pens are you going to buy?—I’ll buy of them so I can give one to my fri

问题补充：

—Which of the two pens are you going to buy?

—I’ll buy of them, so I can give one to my friend.

A. all

B. neither

C. every one

D. both

答案：

A. all

B. neither

C. every one

(答案→)D. both

解析：根据so I can give one to my friend可知两个都买。故选D。