In the context of energy flow through ecosystems, what is the primary role of producers?

• A. They break down dead organic matter and recycle nutrients back into the environment.
• B. They obtain energy by consuming producers and other organisms and converting it into biomass.
• C. They regulate population sizes by preying on herbivores and other consumers.
• D. They convert solar (or chemical) energy into chemical energy stored in organic molecules, forming the base of the food web.

Answer: (D)