How is circular motion formed in a convection current?

Correct answer: By warmer, less dense material rising and cooler, denser material sinking

A convection current forms because temperature differences produce density differences. Warmer material expands, becomes less dense, and rises, while cooler, denser material sinks. The repeated rising and sinking produces circular motion. Option C is incorrect because a uniform temperature does not create the density difference needed for convection. Exam tip: remember: temperature difference → density difference → rising and sinking → convection current.