Answer:
B. Weight of the atmosphere above the surface.
Explanation:
The pressure that the atmosphere of the earth exerts is termed to be the atmospheric pressure. This pressure is applied on the surface of the air because of the gravitational pull. With the increase in altitude, the atmospheric pressure decreases. The atmospheric weight pushes itself downwards because of the gravity, this creates the pressure. The factor that causes atmospheric pressure is the 'Weight of the atmosphere above the surface.'
