Acid rain and snow result from the chemical reactions between industri

This sounds like an attempt to distill SC reasoning down to a list of memorized rules (something like: "if a 'to+verb' answers the question 'why?', it must be acting as an adverb that modifies the verb..."). Such rules are tempting. One less thing to think about on test day, right?

The problem is that "rules" like this encourage you to do the opposite of what you actually need to do on SC, which is to use your brain and think really hard about meaning and context every single time.

So, forget about coming up with a rule, and instead just ask yourself, "What does this word or phrase logically modify? And does that actually make sense?" The GMAT won't ever ask you to label parts of speech, and neither will we.

I hope that helps a bit!