Which of the following facts about the photoelectric effect can be understood without invoking the quantum concept of light propagation

Options

A. The rate of photoelectrons emission, when they are emitted, increases with the intensity of light used
B. There is a threshold frequency, below which no photoelectrons are emitted, no matter how long the light is thrown on the metallic surface
C. Once the frequency of light is more than the threshold frequency, photoelectrons are emitted almost instantaneously, no matter how weak the light intensity is
D. For each frequency of light, exceeding the threshold frequency, there is a maximum kinetic energy of the emitted electrons

Answer

A