When a Sparkler Is Twirled Rapidly, People Perceive a Circle

Multiple Choice

When a sparkler is twirled rapidly, people perceive a circle of light.This occurs because

A) the trail you see is caused by sparks left behind from the sparkler.
B) due to its high intensity, we see the light from the sparkler for about a second after it goes out.
C) the length of iconic memory (the persistence of vision) is about one-third of a second.
D) Gestalt principles work to complete the circle in our minds.