Decomposers are

Explanation:

• Autotrophs: these are the organisms that can make their own food using inorganic sources of materials like H₂O.
• Organotrophs are the organisms that receive material like hydrogen and electrons from organic sources like H₂S. 
• Decomposers are heterotrophs that break down and feed on the remains of dead and decaying matter. 

They secrete digestive enzymes which decompose the organic matter.

Final Answer:

The correct answer option is D, heterotrophs.