听力原文:W: Air security checks in the airport always make me nervous. I'm worried that I'
M: No, I know I'll set off security alarm for sure. I have a steel plate in my arm from a rugby injury.
Q: Why will the man set off the alarm in the airport?
(17)
A.Because he is wearing jewelry.
B.Because he has keys in his pocket.
C.Because he has a mental plate in his bag.
D.Because he has a steel plate in his body.