Which method describes convection?

Convection is a method of heat transfer that occurs primarily in fluids, including liquids and gases, where the warmer portions of the fluid rise and the cooler portions descend, creating a circulation pattern known as a convection current. This process occurs due to differences in temperature and, consequently, differences in density within the fluid.

In the context of your question, choice C accurately captures this definition by highlighting heat transfer through air currents, which is a classic example of convection. The air is heated, becomes less dense, and rises, allowing cooler, denser air to move in and take its place, enabling effective heat distribution throughout the fluid.

The other options describe different mechanisms of heat transfer not involving convection. For instance, the first choice refers to radiation, where heat is transferred by electromagnetic waves without the need for a medium. The second option describes conduction, which is the transfer of heat through direct contact between materials. Lastly, the fourth option pertains to conduction as well, specifically in solid materials where heat is transferred through atomic or molecular collisions. Each of these methods serves specific contexts but does not encompass the convection process as described in choice C.