The Earth's winds are caused by uneven heating of the atmosphere by solar radiation. The uneven heating causes air masses to have different temperatures and densities.

Which of the following correctly explains how these differences cause the air masses to move?
A.
Colder, denser air masses rise in the atmosphere; warmer, less dense air masses sink in the atmosphere.
B.
Warmer, less dense air masses rise in the atmosphere; colder, denser air masses sink in the atmosphere.
C.
Colder, less dense air masses rise in the atmosphere; warmer, denser air masses sink in the atmosphere.
D.
Warmer, denser air masses rise in the atmosphere; colder, less dense air masses sink in the atmosphere.