Final answer:
The primary source of energy in a food chain is sunlight, which is used by producers through the process of photosynthesis and transferred to consumers.
Step-by-step explanation:
The primary source of energy in a food chain is sunlight. Sunlight provides energy to producers (such as plants) through the process of photosynthesis. This energy is then transferred to consumers (such as herbivores and carnivores) as they consume the producers.
Learn more about Primary source of energy in a food chain