C

Step 1: Understand the photoelectric effect, which occurs when light incident on a metal surface causes the emission of electrons.
Step 2: The energy of the incident photons is given by the equation $E = h u$, where $E$ is the energy, $h$ is Planck's constant, and $\nu$ is the frequency of the light.
Step 3: The stopping potential (the potential required to stop the emitted photoelectrons) is related to the maximum kinetic energy of the photoelectrons, which can be expressed as $K.E. = eV_s = h u - \phi$, where $\phi$ is the work function of the material.
Step 4: Therefore, the stopping potential depends on the frequency of the incident light since it determines the energy of the emitted photons.
Step 5: It also depends on the nature of the cathode material, as different materials have different work functions.
Conclusion: Hence, the stopping potential depends on both the frequency of the incident light and the nature of the cathode material.