The learning scientists studying video lessons present the hypothesis that faster playback hurts comprehension because learners miss spoken details. Evidence then sorts the claim into stronger and weaker parts: students at very high speed missed more factual details, but moderate speed did not reduce scores
when captions were on. A third detail - learners with prior knowledge benefited from reviewing more examples quickly - lets the author conclude that high speed can harm detail recall, but moderate speed with support can be useful. Which choice best maps the passage's introduction of a hypothesis and subsequent use of evidence about video playback speed in online learning?
