It is D.) because it would sit there forever to who knows. There is always something that is used from something according to the food chain. Take a dead bird for example. Consumers would not want to eat a bird that has no nutrients that is alive. So this is when decomposers swoop in. Maggots, fungi, worms etc. decompose the dead body and if is was fungi, the nutrient will go into the soil and the process starts again providing nutrients to plants.