What is formed by the movement of hot and cool material inside the Earth?

Correct answer: Convection current

The movement of hot and cool material inside the Earth produces convection currents. Hot material becomes less dense and rises, while cooler material becomes denser and sinks. This continuous circulation transfers heat and can contribute to movements in the mantle and tectonic plates. Therefore, option A, convection current, is correct.

The process can be understood as a repeating cycle rather than a single movement. Heating causes material near a heat source to rise; after reaching a cooler region, it loses heat, becomes heavier, and sinks again. This rising and sinking movement is called convection. A river delta, desert dune, and glacial lake are surface landforms made by other processes and are not produced by this internal circulation. Hence option A follows directly from the definition.