Answer:
(C). They are heterotrophs because their food is made by other organisms.
Step-by-step explanation:
Heterotrophs are those organisms that cannot food by their own and depend on other organisms for their food. Fungi are heterotrophic organisms they uptake there food from other living or dead organisms.
Mushrooms belong to kingdom fungi and uptake their food by decomposing dead remaining of organisms or feeding for energy production.
Thus, the correct answer is option (C).