Barron's 的sat题目,解释是要改写成in which来引导noun clause.In which和where

Barron's 的sat题目,解释是要改写成in which来引导noun clause.In which和where不是等同的吗?
In the aftermath(A) of the space shuttle Challenger explosion,where(B) seven crew members were killed(C),the NASA program underwent a massive examination(D) of priorities.No error(E)