While drafting a short research answer about margin notes, a student reviews these notes: - A literature researcher studied notes written in library copies of a serialized novel. - Some readers wrote guesses about future plot events in the margins. - Later notes showed readers crossing out guesses after new chapters appeared. - The researcher argued that readers treated the novel as an unfolding puzzle. The research question is: "What conclusion did the margin notes support about readers?" Which choice best uses the notes to answer the question?