The correct option is D All of these
Decomposers are the organisms that play a critical role by breaking down and decomposing the body and release the element back to nature for other organisms. Thus they help in recycling the nutrients in the atmosphere. They also act as the cleaning agent of the environment because without them dead organisms will pile up. Thus in their absence all the organisms i.e., plants, animals, and insects will be affected. Thus, the correct answer is option D.