How does convection transfer heat?

Convection transfers heat by the actual movement of heated material, which is a fundamental principle in thermodynamics and fluid mechanics. In convection, warmer areas of a fluid (liquid or gas) become less dense and rise, while cooler areas become denser and sink. This creates a continuous circulation pattern known as a convection current. This process efficiently distributes heat throughout the fluid as the warmer, less dense regions rise and the cooler, denser regions sink, thus transferring thermal energy in the process.

The other options relate to different mechanisms of heat transfer. Direct contact of solid surfaces describes conduction, where heat is transferred through physical contact without the movement of the materials themselves. The conversion of liquids into gas pertains to evaporation or boiling, which involves a phase change rather than bulk movement of the fluid. Finally, losing heat specifically from non-insulated body areas relates to heat loss mechanisms but doesn't characterize the process of convection itself. Hence, the movement of heated material through convection is the correct understanding of how this process works.