Which of the following phenomena is not explained by the wave nature of light?
$(A)$ Reflection
$(B)$ Diffraction
$(C)$ Photoelectric effect
$(D)$ Interference
$(E)$ Polarization
Choose the most appropriate answer from the options given below:

The figure shows the variation of photocurrent with anode potential for a photo-sensitive surface for three different radiations. Let ${I_a}, {I_b}$ and ${I_c}$ be the intensities and ${f_a}, {f_b}$ and ${f_c}$ be the frequencies for the curves $a, b$ and $c$ respectively.

Photo cells convert

Light with a frequency of $1.5$ times the threshold frequency is incident on a photosensitive material. If the frequency is halved and the intensity is doubled,what will be the photoelectric current?

From the photoelectric effect experiment, the following observations are made. Identify which of these are correct:
$A.$ The stopping potential depends only on the work function of the metal.
$B.$ The saturation current increases as the intensity of incident light increases.
$C.$ The maximum kinetic energy of a photoelectron depends on the intensity of the incident light.
$D.$ The photoelectric effect can be explained using the wave theory of light.
Choose the correct answer from the options given below:

From the following graph of photo-current against collector plate potential,for two different intensities of light $I_{1}$ and $I_{2}$,one can conclude: