Question

What causes warm air to rise?

a. The fact that it's less dense than cold air.
b. The fact that it weighs more than cold air.
c. The fact that it has higher pressure than cold air.
d. The fact that it's more dense than cold air.

Answer 1

The answer is a because it reverses depending on the temperature

Answer 2

a. The fact that it's less dense than cold air.