D

Step 1: According to the photoelectric effect, the kinetic energy (KE) of photoelectrons is given by the equation:
$$ KE = hf - \phi $$
where h is Planck's constant, f is the frequency of the incident light, and \phi is the work function of the material.

Step 2: From this equation, it is clear that the maximum kinetic energy of the emitted photoelectrons depends on the frequency of the incident light f. The greater the frequency, the higher the kinetic energy.

Step 3: Other factors such as incident angle, potential, and pressure do not influence the maximum kinetic energy of the photoelectrons. Therefore, the correct answer is based solely on the frequency.

Therefore, D.