→ Autotrophs are the organisms that make their own food, meaning they don't need to hunt/look for anything, such as plants.
→ Heterotrophs are animals that are incapable of producing their only nutrients, so they depend on an external source of energy which they obtain by hunting, scavenging, etc.
So in a way, heterotrophs make food for autotrophs, because in their excrements, there is still nutrients which can be useful to plants.
Answer:
![\boxed{\bf~C.~Hetertrophs~make~food~for~autotrphs.}](https://img.qammunity.org/2019/formulas/biology/middle-school/530yj626eufqxbs6kzbr72u5qxqj5d1tyl.png)
Hope it helped,
BioTeacher101