Answer:
The best answer would be D, all of the above.
Step-by-step explanation:
Option A counts since too much rats would be bad for plants since the plants will just die out, then no food for rats, so they die out, then snakes die out from not food, then eagles, you get it. If there's too much snakes, it's bad for rats and the rats die out, means the plants over populate, then no food for snakes, so they die out, etc. It's important to have such trophic system in any habitat.
Option B counts since not all energy is past down. Plants can get the most out of energy since all they do is collect it. Meanwhile animals can't since they're always on the move, meaning that energy is lost. This is why 10% of energy is lost on each level.
Option C counts since, well isn't it obvious? Look outside. You know, there's a lot of different trees, flowers, grass, etc. Now look at birds or insects. Not as much, but still pretty diverse. Then maybe look at cats or dogs. It's clear that it's less diverse. Then raptors and bears? Not very diverse, there's a few types like hawks, falcons, polar bears, but it's not very much.
So the best option would be D, all of the above.