Which one of the following is a secondary consumer?

A food chain groups organisms into trophic levels based on diet: primary consumers are herbivores that feed directly on producers (plants); secondary consumers are carnivores or omnivores that prey on primary consumers; tertiary consumers, the apex predators, prey on secondary consumers and sit at the top of the chain.

The snake preys on small herbivorous animals such as rodents. Since its prey are themselves primary consumers, an animal that feeds on them sits one trophic level higher — at the secondary-consumer level.

• Elephant feeds directly on grasses, leaves, and shrubs, so it is a primary consumer, not a predator of other animals.

• Goat likewise grazes directly on vegetation, placing it at the same primary-consumer level as the elephant.

• Lion is conventionally classified as the apex predator at the top of the food chain, placing it at the tertiary-consumer level, one step above a secondary consumer — even though its specific diet can vary between different food chains.

Among the four, only the snake fits the secondary-consumer role of an animal that preys on herbivores without itself being the apex predator.