The correct answer is food chain.
The food chain can be defined as the transfer of energy from the producers and ends on consumers.
The producers make food by the help of photosynthesis using sunlight.
Example: Green plants and blue-green algae.
Then comes the consumers that eat the producers to obtain energy. The animals that feed on producers are called as primary consumers. Example: rabbit.
The animals that feed on primary consumers are called as secondary consumers.
Example: lion.
