A) Radiation
B) Conduction
C) Convection
D) None of the above
The correct option is A) Radiation.
Radiation is the fastest mode of heat transfer while conduction is the slowest mode of heat transfer.
Radiation is defined as the mode of heat transfer which takes place through the vacuum and doesn’t require any physical medium.
Sunlight is an example of radiation. Radiative heat transfer is usually governed by Stephen-Boltzmann law.