Answer:
(4) deer eating grass
Explanation:
In ecology, a pattern of feeding exists through which organisms obtain energy by feeding on one another. This pattern is called FOOD CHAIN. Each organism of the food chain are classified into into steps called trophic level based on their feeding behavior.
The first level contains unique set of organisms called AUTOTROPHS, based on their ability to produce their own food. These autotrophs are usually plants in a terrestrial environment. They are called PRIMARY PRODUCERS. They are the lowest level in the food chain.
These producers are eaten by another set of organisms called PRIMARY CONSUMERS. They are dependent on plants for food and energy source, hence, called heterotrophs.
In this question, the grass represents the producer, which will be fed upon by a herbivorous deer (consumer)
