Answer:
a.aquatic plants
Explanation:
The energy stored in organic matters, which can be used as fuel for various purposes. This the same energy obtained from the sun that is passed on to each tropic level by the 10% law. This is known as biomass energy.
Biomass is highest at the first trophic level in any food chain. In the aquatic food chain also the highest biomass at the first trophic level which aquatic plants.
Hence option a is correct.