Answer:
Food source and space.
Explanation:
With more animals, more food and space is required. With a sudden growth there may not be enough sufficient.
The food source could quickly run out, and same with space.
Plants because they go through photosynthesis
Now that I think about it, it would be A and B because you need your bones for support and they also protect your organs. As for D it's the other way around your muscles help your bones move.
