What is air pressure?
a. earth's gravity pulling down on air molecules.
b. constant collisions between air molecules due to their high energy
c. the result of air being confined to a particular volume in the atmosphere
d. the sun's gravity pulling on earth's atmosphere

A. Earth's gravity pulling down on air molecules

Explanation:

Air pressure refers to the weight of the air per unit surface area. It is the amount of gravitational force which is pulling down the molecules of air.

The common unit of air pressure is: Pascal, atm

1 atm = 101325 Pa

As the column of the air above increases, the air pressure increase. This is because with the increase in amount of air, the weight increase of the air increases. This is the reason a diver feels immense pressure in the sea and cooking takes a lot of time on hilly areas because of low air pressure.

(A.) earths gravity pulling down on air molecules

Explanation: