Question

What is an effective way of organizing information in an outline for a research paper?

Answer 1

I think the answer is the third one.

Answer 2

I would also say that an effective way of organizing information in an outline for a research paper is the third option - dividing the information into various sections noted by numbers or letters.
You can easily arrange these sections in the text later on, but you need to have all of your ideas placed in the appropriate section beforehand so as to make your job easier.