Question

as altitude increases, what happens to air pressure?
○ it fluctuates.
○ it increases.
○ it decreases.
○ it stays the same.

Explanation:

Air pressure is the force exerted by the weight of air molecules. At higher altitudes, there are fewer air molecules above a given point. This means the weight of the air column (and thus the pressure) is less. Fluctuation would imply irregular changes, which isn't the general trend. An increase would require more air molecules (opposite of what happens with altitude). Staying the same ignores the change in the amount of air with height.

Answer:

It decreases.