M: I recently read that in ten years we'll wearing clothes that change with the weather. So when it's cold, our clothes will warm up, and when it's hot, our clothes will cool off.
W: Oh, very funny. So we'll be wearing huge clothes with built-in air conditioners and heaters.
M: I'm serious. Researchers have discovered a method of treating fibers with plastic crystals which can store and release heat as the temperature changes. These treated fibers absorb more heat than untreated fibers. Researchers are still working with this, but soon this process will be widespread.
W: That's fascinating. I didn't know that fibers could store heat. How does that work？
M: These fibers work with the heat by rearranging their structures.
W: That's truly unbelievable. You said that it'll be a decade before this type of clothes will be available. What a shame! I don't think I can wait that long.
What's the man's first reaction to what the woman describes？

A. He is shocked.
B. He is excited.
C. He is upset.
D. He is doubtful.