Safety in school has been of great concern because of frequent reports about accidents s

问题补充：

Safety in school has been of great concern because of frequent reports about accidents students got injured or killed while in school .

A. that

B. when

C. in which

D. for which

答案：

A. that

B. when

(答案→)C. in which

D. for which

解析：考查定语从句。句意“校园安全已经引起了很大的关注，因为学生在学校受伤或死亡的频繁报道。”而定语从句不缺少成分，先行词accidents“在事故中”，指抽象的地点，故用where或in which。故选C。