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:

• A
  $B$ only
• B
  $A, C, D$ only
• C
  $B, C$ only
• D
  $A, B, D$ only