单项选择题

M: I want to make sure my son receives this letter. It has an important certificate in it.
W: You can send it either by certified mail or registered mail. If you only want to make sure it is received, send it by certified mail. It’s less expensive.
M: OK. How about this package
W: What’s in it
M: A watch.
W: You should insure it for the value of the watch, and sent it by registered mail. It’s more expensive, but it’s the safest way.

In which way do you think the man will send the letter()

A. By certified mail.
B. By air mail.
C. By registered mail.
D. $33.00.