What happens next?

How to talk to a girl in class
Ask a small favor.
The easiest way to begin a conversation with someone you want to talk to is to ask a favor. You don't know this person yet, so you don't know what you have in common.

Options:
[A]. Asking a favor will help you confirm that this person doesn't have a girlfriend/boyfriend, just has a crush on you. It's appropriate to ask, say, " hey sarah, i saw you in the hallway.;
[B]. Asking something easy like " i saw your note " may not be the best kind of favor. However, don't go around asking big-umbrella solutions.;
[C]. Asking a favor is a neutral way to enter into conversation without boring them with something they don't care about. Make sure it's a small favor that won't put her out.;
[D]. After asking the girl how her day is going, find out what class she's in. Asking someone for a favor just isn't possible.;
[C].