Do you know Mo Yan?—Of course. He is the famous writer won the Nobel Prize in 2012.A.

-- Do you know Mo Yan?
—Of course. He is the famous writer won the Nobel Prize in 2012.
A. who B. whom C. which

解析：who谁，做引导词指人；whom 谁，做引导词指人，作宾语； which哪一个，做引导词指物。句意：你知道莫言吗？——当然了。他是在2012年获得诺贝尔奖的著名作家。结合语境可知本句先行词the famous writer为下文定语从句的逻辑主语，指人，故选A。

和我的回答一样，看来我也对了