Saprotrophs are organisms that obtain their nutrition from dead and decaying organic matter. They secrete digestive enzymes onto the matter and absorb the simpler nutrients that result from the breakdown. Fungi and some bacteria are prime examples of saprotrophic organisms. Explanation of other options:
(A) Autotrophs produce their own food via photosynthesis — incorrect.
(B) Heterotrophs consume living organisms for energy — incorrect in this context.
(D) Symbiotic organisms live in association with another species, often with mutual benefit — not the correct term for decomposers.