The correct answer is B) Sunlight.
Sunlight is the main source of energy that flows through the ecosystems via different trophic levels.
A few percentage of sunlight is termed Photosynthetically active radiation (PAR). This light has a wavelength of 400-700 nm. This is the light that plants use for the process of photosynthesis.
Plants use this energy to convert water and carbon dioxide into glucose and oxygen with the help of chlorophyll. The glucose formed is the energy product of the reaction.
So plants are called producers because they can make energy by their own. Consumers consume plants for energy requirements and so on.
Know more about trophic levels here:
https://brainly.com/question/13267084
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