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 send it by registered mail. It's more expensive, but it's the safest way., Question: What is in the letter? (A) A valuable book. (B) An important certificate. (C) A beautiful postcard.
(B) An important certificate.