Answer: Biology
Step-by-step explanation:
Biology can be defined as the field of science that deals with the study of interaction between animal-human, animal-nature, human-nature, animal-animal, et cetera.
If somebody wants to study the interaction between the producers, consumers and decomposer. Then he should study biology. This is because the interaction between the plants and the animals is a part of ecology.
Hence, the correct answer is option D