Answer : Option C) Max Planck
Explanation :
To explain the photoelectric effect, Albert Einstein linked the photoelectric effect to an idea from Max Planck.
Einstein's photoelectric effect was based upon Max Planck's theory of black-body radiation, where his theory was based on the energy which was present in each quantum of light is equal to the frequency and multiplied by a constant, which was later called Planck's constant.
A photon that had frequency above threshold frequency was the required energy to eject a single electron, creating the photoelectric effect.
