Answer:
Prey.
Step-by-step explanation:
Food chain may be defined as the sequential steps of the different trophic levels in which the organism eats other organism and itself being eaten by other organism. Food chains are not exist in nature.
The quaternary consumers are at the highest level on the food chain. They can acts as the predators and animals. But they cannot acts as prey as they kill or eat other organism but the lower organism cannot kill them.
Thus, the correct answer is option (b).