It is reported that no problems have been discovered in milk products such as Yili, Sanlu and Mengniu, proves newly-produced liquid milk safe.
A. that
B. what
C. which
D. where
网友回答
A. that
B. what
(答案→)C. which
D. where
解析：考查定语从句，which引导定语从句指代前面的句子，并且在定语从句中做主语。