Answer: b). plants or producers
The food chain is the linear sequence of transmission of food and energy when one organism is consumed by the other organism. In the energy pyramid of the food chain plants obtain the lower most trophic level which is called as producers. Plants are called as producers or primary producers because they are abundantly present in nature, they are able to synthesize their own food by photosynthesis and large population of animals species relies on them as a source of energy. Therefore, plants or producers are the organisms that have the most energy available in the food chain energy pyramid as the energy decreases from the lower to subsequent higher trophic levels.