In a double-slit experiment, electrons are fired at an opaque barrier having two small slits, and a screen beyond the barrier records where the electrons hit. After many electrons are fired, what is observed on the screen?

A. The pattern observed indicates that electrons struck only the areas of the screen directly across from the two slits.

B. The pattern observed indicates that electrons struck the screen directly across from the two slits and the center of the screen

C. The pattern observed indicates that electrons struck only the center of the screen.

D. The pattern observed indicates that electrons struck the screen in alternating bands across the screen.