Convection occurs exclusively in which types of matter?

Convection is the process of heat transfer that occurs through the movement of fluids, which can include both liquids and gases. The key characteristic of convection is that it relies on the motion of the fluid itself to transfer heat. As a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks. This creates a circular motion known as a convection current.

Solids do not participate in convection because they cannot flow or move in a way that allows the heat transfer mechanism typical of fluids. While in a solid, heat transfer primarily occurs via conduction, where thermal energy is transferred through direct contact between particles.

Since convection occurs in both liquids and gases, the broader term "fluids," which encompasses both, aptly describes the conditions under which convection happens. Hence, the correct answer is that convection occurs exclusively in fluids.