A、Smith’s. B、Brown’s. C、Susan’s. D、Bob and Brown’s. A根据选项，推测对话内容中会出现一些人的名字。打电话的人是Smith仇的秘书，因此A为正确选项。

W: Whereas European nations have traditionally employed metric units such as meters and grams, the U.S. has employed English units such as feet and pounds.
M: Both systems are now in use in the U.S., though.
Q: What are the two people talking about?

W: Hello, Mr. Brown. This is Susan, Bob Smith’s secretary. I am calling to confirm his appointment with you at 10 o’clock today.
M: Thanks for calling; I’ll expect Mr. Smith at 10 o’clock.
Q: Whose secretary is calling?