Of the four methods of heat transfer: conduction, advection, convection, and radiation, which one is considered the most important method of heat transfer?

Radiation

Explanation:

Radiation - Radiation is the mode of transfer of energy wave in the form of motion wave through the medium. some example of radiation are: infrared, x-ray. micro-wave, electromagnetic radiation, etc. it is way of giving off  of  energy by any medium in the form of wave particle.

Long term exposure of radiation also able to cause cancer and normal effect  of radiation includes skin disease,  radiation disease, etc.