The correct answer is option 2 - Convection. Trade winds are systematic prevailing winds that blow from east to west in the Earth`s tropical regions. They are caused by the movement of warm air near the equator towards the poles and cooler air from the poles towards the equator. This movement is driven by convection, which is the transfer of heat through the movement of a fluid, in this case, air. As the warm air rises near the equator, it creates a low-pressure area, and the cooler air from the poles rushes in to fill the void, creating the trade winds. Therefore, convection plays a crucial role in the formation of trade winds.