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
网友回答
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。