Please help me i don’t understand this

So this is like a food chain chart. The animals at the top are one top of the food chain and do not get eaten by anything; they dont have any predators. This chart goes from bottom up. So the plants have arrows pointing to animals. Those animals that the plants are pointing to are the animals that eat that plant. And then those animals point to another animal higher on the chain and those animals that are higher eat the animals that are lower than them and have the arrow pointing at them. So the snake is pointing to the owl because the owl eats the snake. The frog is pointing to the snake because the snake eats the frog. And the list on the side of the chart is just a list of different kinds of animals. I dont remember what each of them are so you are going to have to find out what element is missing.

Explanation:

b is the answer and if you need further with anything message me