Gervase Is Staring at the Blades of His Ceiling Fan

Gervase is staring at the blades of his ceiling fan, searching for inspiration for a paper that he is writing.When he turns off the fan, he is very surprised that the blades appear to be rotating in the opposite direction.To reassure Gervase that he is not hallucinating, you could tell him about

A) stroboscopic motion.
B) motion aftereffects.
C) compensatory motion.
D) object constancy.