In the photoelectric effect, electrons are never emitted from a metal if the frequency of the incoming light is below a certain threshold value. This is because

A. Photons of lower-frequency light don't have enough energy to eject an electron.

B. The electric field of low-frequency light does not vibrate the electrons rapidly enough to eject them.

C. The number of photons in low-frequency light is too small to eject electrons.

D. Low-frequency light does not penetrate far enough into the metal to eject electrons.