Question

what is the best definition of air pressure as it is used in the passage?
force exerted by a weight of air
flight of air into the atmosphere
fluid contained by columns of air
flowing of air to different regions

Explanation:

Air - pressure is the force per unit area exerted on a surface by the weight of the air above it in the atmosphere. The other options do not accurately define air - pressure.

Answer:

force exerted by a weight of air