听力原文：W: I think we ought to turn around and head back down thc trail.
M: Tired, after just a few miles？
W: Not at all, but those are cumulonimbus clouds building up there.
M: So, I don't really care if it gets cloudy. The sun's been pretty strong.
W: Right, but those clouds mean a thunderstorm, lots of rain and sometimes even hail with those kinds of clouds.
M: That doesn't sound so great, but I thought that these cumulus what it's were fair weather clouds.
W: You are thinking of cumulus clouds I bet. Those are definitely cumulonimbus.
M: How on earth did you ever learn all that, from a meteorological course？
W: I'm an English major, but growing up on a farm, you learn a lot about weather.
M: You convince me, let's turn back, and maybe on the way down, you can give a lesson on clouds.
W: A sure thing, but let's get going.
(20)

A. Convince the man that they should rest for a while.
B. Teach the man about the types of clouds.
C. Entertain the man with some interesting weather stories.
D. Persuade the man to turn around and go down the hill.