It was there， the police believe， ______ she was able to activat

It was there， the police believe， ______ she was able to activate the recorder she kept in her bag.
A、until
B、which
C、that
D、when
【正确答案】：C
【题目解析】： 本句考查强调句的用法。the police believe在句中作插入语，我们可以将其去掉再解题。本句的意思是“她正是在那里打开了包里的录音机”。强调句一般要用that来连接，因此本题的正确答案是C。