The answer for this question is B. D would represent corn. C would represent the insects that feed on corn. Since birds feed on insects, they will occupy the B level of the pyramid. The A-level will be represented by a predator that feeds on birds. Take note that there are different animals that can be placed on the various pyramid levels depending on their feeding habits.
A lot of times, humans end up in A because people are the primary consumers whether of various animals and even vegetables. Understanding this type of pyramid will give people a better understanding of the world’s ecosystems.