Answer:
Decomposers are prey.
Step-by-step explanation:
Decomposers break down (hence, 'decompose') dead organisms, and are heterotrophs, but are not predators. They do not actively go hunting, nor consume food like a predator typically would, and are not technically scavengers.
However, they are eaten. We eat mushrooms and fungi all the time. Other animals eat them. This constitutes them as prey.