Answer:
Genetic variation is the difference in DNA among individuals or the differences between populations. There are multiple sources of genetic variation, including mutation and genetic recombination.
Explanation:
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.
I’m pretty sure it’s adenosine diphosphate