The answer is observations
I think the best answer would be A. since the number of prairie dogs decreased from the picture on the left to the picture on the right. Hope this helped :p
There are so many examples for that in different areas, like biology experiment carried out in our lab recently.
Here's one linhttps://www.creative-biogene.com/support/Lentiviral-Vectors-the-Application-for-CAR-T-Therapies
k:
Atmosphere is the correct answer!
Is any member of a large class of gaseous, liquid, or solid chemical compounds<span>whose molecules contain carbon</span>
