听力原文：W: I think we ought to turn around and head back down the 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 those cumulus were fair weather clouds.
W: You are thinking of cumulus clouds I bet. Those are definitely cumulonimbus.
M: How on earth did you ever hear all that, from a meteorological course?
W: I'm an English major, but growing up on a farm, you learn a lot about the weather,
M: You convince me, let's turn back, and maybe on the way down, you can give a lesson on clouds.
W: Sure thing, but let's get going.
Where does the conversation take place?
A．On a mountain trail.
B．In a classroom.
C．At a weather station.
D．At a planetarium.