Final answer:
None of the given options will lead to a decrease in the kinetic energies of photoelectrons emitted during the photoelectric effect. The intensity and temperature changes influence the number of electrons, not their kinetic energy, while frequency increase leads to higher kinetic energies.
Step-by-step explanation:
The subject of the question is Physics, specifically related to the photoelectric effect. The question asks which situation will lead to a decrease in the kinetic energies of photoelectrons emitted when light is incident on a metal surface. Increasing the intensity of light does not affect the kinetic energy of the photoelectrons but increases their number. Increasing the frequency of light will increase the kinetic energy of the photoelectrons. Decreasing the work function of the metal would lower the threshold energy, potentially allowing for more electrons to be emitted without altering their kinetic energy directly. Increasing the temperature of the metal could lead to a minor increase in the number of electrons emitted due to increased thermal energy, but it doesn't directly decrease the kinetic energies of the photoelectrons. Therefore, none of the options provided will necessarily lead to a decrease in the kinetic energies of photoelectrons.