Man: Have they found anything about the girl's death Woman: I think so. The report they would present to the police station will throw light on it. Question: What does the woman mean

A．The mystery of the girl's death will be clamped.

B．The mystery of the girl's death will be clarified.

C．They can never find the answer to the girl's death.

D．They can never trust the police station for cracking the mystery.

（）是保证系统安全的有效方法

A.口令

B.身分验证

C.设置防火墙

D.尽量不开机