Which could be a pathway of food through an ecosystem?

Sun > Grass > Deer > Lion

Explanation:

The sun begins a food chain because its light is needed for a plant, in this case grass, to grow.

An animal that eats grass is the deer, who is a primary consumer.

An animal that eats deer is the lion, who is a tertiary consumer in this case.

The lion has no natural predator, and thus is at the top of this food chain.

This ecosystem can be one found where grass, deer and lions exist, for example, the deciduous forest in the eastern United States.