Answer:
The correct answer is option A, the flow of energy in an ecosystem
Explanation:
In a food chain & food web, the organism producing the food (known as producer) remains at the lower level is a food pyramid. The producer transfers 10% of its energy to next level of food pyramid i.e the primary consumer and remaining 90% of energy is retained. In the next level, secondary consumer receives 10% of energy from the primary consumer and rest 90% is retained. Likewise in the last stage, 10% of energy is transferred to the tertiary consumer.