Answer:
A. air pressure,this is answer.
What kind of control like scientific?
Answer:
The reason is because Flagstaff is at a higher elevation than Phoenix.
Explanation:
The air is thinner at higher elevations. You can google Flagstaff's elevation compared to Phoenix but the simple answer is that air is thinner at higher elevations and some people used to 'thicker' air find it harder to breath, especially after some strenuous exercise.
Where’s the question or equation
The straight horizontal line shows us that the object is moving at a constant speed