The correct answer is D. All of the above.
Heat is generated in a H.R.C. fuse when an electric current passes through it. This heat is dissipated through a combination of radiation, convection, and conduction.
Radiation is the emission of energy in the form of electromagnetic waves. The heat generated in a H.R.C. fuse is radiated away from the fuse in the form of infrared radiation.
Convection is the transfer of heat by the movement of fluids. The heat generated in a H.R.C. fuse causes the air around it to circulate, which helps to dissipate the heat.
Conduction is the transfer of heat through direct contact. The heat generated in a H.R.C. fuse is conducted through the fuse material to the surrounding metal parts, which helps to dissipate the heat.
All of these methods of heat dissipation work together to keep the H.R.C. fuse from overheating and melting.