Hi. For an application for Advance Parole, on form I-131, Part 1, Question 3 "Class of Admission" what is that? Are they asking what kind of visa was used to enter the US? Or asking for refugee status or what? Thanks.

Just like the K1 process, there are Guides, FAQs and Example forms for the AOS process.
http://www.visajourney.com/examples/INS-Form-I-131.pdf

Thanks. That's what I thought. "Class of Admission" is strange field name to use.