It's just the way the French speak about the weather. See http://french.about.com/od/vocabulary/a/weather.htm for example.
Boy, I don't know if it was my hearing or the quality of my audio, but even after I saw what the right answer was I could not understand "bronze" or any word starting with a b. And I got this isolated as part of a general review, so I had no contextual clues other than the first part of the sentence.
I think if you are saying a PERSON is feeling hot (inside their body), you use avoir (so: Il A chaud, j'AI chaud) and if you're talking about an object that feels hot to the touch, you use etre (la plaque chauffante EST chaud)... This is from what I remember learning a few years ago at school!
http://www.frenchtoday.com/blog/chaud-and-froid-in-french Read this to understand easier (I'm rubbish at explaining things!)