How do convection currents form? A. When heated air expands, it becomes less dense, rises, and displaces cooler,
more dense air, which moves downward.
B. When heated air expands, it becomes more dense, falls downward, and displaces cooler, less dense air, which rises.
C. When cooled air contracts, it becomes less dense, falls downward, and displaces warmer, more dense air, which rises.
D. When cooled air contracts, it becomes more dense, rises, and displaces warmer, less dense air, which falls downward.