Consider this ecological pyramid found in Great Lakes ecosystem. Ecological pyramids are diagrams that are used to show how much energy the number of organism or how much biomass may be found at each tropic level of all the food webs of a community. Why are the autotrophs, in the case the algae, always placed at the base of the pyramid ?

A) autotrophs are always the most numerous in any ecosystem

B) autotrophs are the starting point of the carbon cycle in any ecosystem

C) autotrophs are responsible for converting solar energy into usable chemical energy

D) autotrophs work with saprophytes and detritivores to recycle energy into the food web