Photoelectric effect supports quantum nature of light because
There is a minimum frequency below which no photoelectrons are emitted
The maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity
Even when the metal surface is faintly illuminated the photoelectrons leave the surface immediately
1. Wave model couldn’t explain the presence of a threshold frequency only after which the photo electrons started coming out.
This was explained by the photon model
2. According to the wave theory the maximum kinetic energy of photo electrons should increase on increasing the intensity and shouldn't depend on frequency but again the observations did not match and it was seen that the maximum kinetic energy of the photo electrons varied on changing frequency and not intensity. Again this was explained by the photon model of light.
3. The wave theory predicted a delay in the coming out of photo electrons on reducing intensity but we saw that even if the intensity is reduced but frequency is above threshold frequency then still electrons come out immediately. This again was a drawback for the wave model but was explained by the photon model of light.
So a,b,c is correct .
Option d is incorrect as electric charge of all photo electrons are going to be the same , they are electrons , all electrons have the same charge.