The question is asking to choose among the following choices that states the mechanism that would explain the said problem. In my own research and further investigation, I would say that the answer would be Genetic Drift. I hope you are satisfied with my answer and feel free to ask for more
Answer:
The circulatory system
Explanation:
The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH,
Amount of rainfall
I’m not sure if this is right but I think it is because all of the rest are major parts of ecosystems, and although rainfall is too, it’s more of a natural source that happens anywhere whereas the rest of the options may determine the ecosystem
C. None of these
it's the oxygen cycle which the option isn't available