premise: B: Um, gee, I don't, I mean, I guess it's the stuff that comes out of automobile exhaust, you know, they say in the paper nitrous oxides and ozone and all that. A: Right. B: So, I believe them but I'm not a chemist. A: uh, do you think that those are bigger contributors than things like acid rain and some of the pollutants that come from, uh, industrial areas, factories and so on?
hypothesis: nitrous oxides and ozone are bigger contributors than things like acid rain