Answer: 0.69 m/ mile.
Explanation:
The altitude gradient between two cities X and Y = 
Given: Two cities are separated by 200 miles.
City X has an altitude of 122 meters.
City Y has an altitude of 260 meters.
The altitude gradient between two cities X and Y =

Hence, the altitude gradient between the two cites = 0.69 m/ mile.
Lactic acid buildup when you’re exercising causes a build up of oxygen. Your body cannot break down glucose in the blood. So, your heart beat increases because there is more oxygen than normal needing to be pumped throughout the body.
In short terms: because your heart needs to pump more oxygen, it is pumping faster causing a faster heart rate.
Answer:
The volume of pollutants decrease in the ecosystem
Answer:
oxygen
Explanation:
we need oxygen don't mind me