As part of his instruction for doing a research paper, Mr. Lee teaches the students to dissect similar research papers and use the strategy of working backward to systematically identify the steps needed to write their own. As a strategy, this general rule of thumb he is teaching them might best be described as

a heuristic

Explanation:

Heuristics are mental shortcuts used by people when finding solutions to problems and when making efficient and hasty decisions and judgments. They shorten the time used in making decision and allows people to make judgments without thinking of their next line of action. Mr. Lee is therefore using heuristics by teaching the students how to use shortcuts (dissecting similar research papers) to achieve writing their own research paper.

i would say b. research typically uses a variety of sources