The correct option is C fresh water ecosystem
In fresh water ecosystem or aquatic ecosystem, a food chain typically starts with phytoplankton and ends at large fishes. Phytoplankton although at the lowest trophic level and form the base, they have the least biomass and the biomass increases gradually towards the top of the pyramid which consist of the big fishes having maximum biomass in the entire food chain. Thus the pyramid of biomass is inverted.