Questions 11～13 are based on the following conversation. You now have 15 seconds to read Questions 11～13.

Why is it necessary to give a coin to someone when you give him a present with a sharp edge or point

A．To specially celebrate his birthday.
B．To express some special meaning which you dare not tell directly.
C．To wish for a long-lasting friendship.
D．To wish your friend good luck in his life.