Air pressure is greatest because there are more molecules of air pushing down from above. a. at the top of the mountain c. in the troposphere b. at sea level d. in the exosphere

Air pressure is greatest at sea level because there are more molecules of air pushing down from above.

Explanation:

The number of air molecules above a surface determines air pressure. As the number of molecules increases, they exert more pressure on a surface, and the total atmospheric pressure increases. By contrast, if the number of molecules decreases, so too does the air pressure.