Correct Answer - B
(b) : There is no emission of photoelectrons till the freaquency of incident light is less than a minimum frequency, however intense light it may be. In photoelectric effect, it is a single particle collision. Intensity is `hvxxN`, where hv is the individual energy of the photon and N is the total number of proton. In the wave theory, the intensity is proportional, not only ti `v^(2)` but also to the amplitude squared. For the same frequency, increase in intensity only increase the number of photons (in the quantum theory of Einstein).