An increase in genetic variation
Answer:
I'm pretty sure the answer is 4.
Explanation:
1 and 2 are definitely homeostasis because it is a way to keep your body balanced how it needs to be and 3 would be a natural reaction that your body would make to prevent further pain, but 4 would be a personal choice that is made by the person who stays up.
<span>Amount of salt is the dependent variable</span>
The temperature would be the independent variable because it is what is being changed or controlled to test the effects.