What is the primary mechanism for heat transfer through liquids and gases?

The primary mechanism for heat transfer through liquids and gases is convection. This process involves the movement of fluid caused by temperature differences within the fluid itself. When a fluid is heated, the molecules gain energy and move more rapidly, causing them to spread apart and become less dense. This less dense, warmer fluid rises, while cooler, denser fluid moves down to take its place. This cycle creates a continuous flow that transfers heat within the liquid or gas.

In contrast, conduction refers to heat transfer through direct contact between materials, and is more effective in solids than in fluids. Radiation involves the transfer of heat through electromagnetic waves and does not require a medium, making it effective in a vacuum, but it is not the primary means of heat transfer for fluids. Induction, while related to electromagnetic fields, is not a method of heat transfer like the others listed. Hence, the correct identification of convection illustrates its crucial role in heating and cooling processes in fluids.