A mushroom gains its energy by decomposing the tissues of dead organisms. Should mushrooms be classified as autotrophs, heterotrophs, in both groups, or in neither group, and for what reason?

They are heterotrophs because their food is made by other organisms.

They are autotrophs because decomposition is very similar to photosynthesis.

They are both autotrophs and heterotrophs, because they may grow in sunlight or darkness.

They are autotrophs because they do not eat their food, as animals do.