The MoSCoW method (Must have, Should have, Could have, Won’t have) is a prioritization technique commonly used in agile to determine which stories deliver the most value. The PMI Agile Practice Guide (Section 5.1: Prioritization Techniques) lists MoSCoW as one of the methods used by product owners and teams to prioritize backlog items.
Option A is correct: MoSCoW is a proven agile prioritization method.
Option B is used for estimation, not prioritization.
Option C is not a standard agile prioritization method.