The right answer is C) convection.
Convection (thermal) refers to the transfer of thermal energy within a moving fluid or between a moving fluid and a solid wall. This transfer of energy is achieved by two modes of "elementary transfer" combined that are advection and diffusion.
Convection (thermal) constitutes, with (thermal) conduction and (thermal) radiation, one of the three modes of heat exchange between two systems, and differs from them by the transfer method.
Thermal convection occurs when the body is in direct contact with the fluid.
