Campbell and Mayer (2009) Tested College Students During Classes

Campbell and Mayer (2009) tested college students during classes.In one condition, students in an Educational Psychology class received a PowerPoint presentation in which questions were included as part of the presentation.In another set of PowerPoint, only statements were made.They found that:

A) the PowerPoint slides were insufficient for any accurate learning to take place.
B) the PowerPoint with questions led to better retrieval from the college students.
C) because the statements contained factual information, the statement condition led to superior recall.
D) the retrieval practice effect did not work with these real world stimuli.