The Photoelectric Effect Exhibits a Threshold Effect That Can Be

The photoelectric effect exhibits a threshold effect that can be stated as follows:

A) There is a minimum incident radiation frequency to eject electrons from a metal.
B) There is a minimum incident photon energy to eject electrons from a metal.
C) Electrons in a metal are attracted by a force that must be counteracted for ejection to occur.
D) All of the above are correct.
E) None of the above is correct.