Question

1. why do convection currents rely on gravity?

gravity causes the cool material to sink while hot material rises.
gravity causes hot and cold to swirl horizontally but not mix.
gravity is not needed in convection currents.

Explanation:

Convection currents form when heated material expands, becomes less dense, and rises; cooler, denser material sinks due to gravity. This sinking and rising motion drives the current, so gravity is essential for this vertical movement.

Answer:

Gravity causes the cool material to sink while hot material rises.