In Any Ecosystem, Terrestrial or Aquatic, What Group(s)is (Are)always Necessary

Question

In any ecosystem, terrestrial or aquatic, what group(s)is (are)always necessary?
A) autotrophs and heterotrophs
B) producers and primary consumers
C) photosynthesizers
D) autotrophs
E) green plants

Accepted Answer

Autotrophs are necessary in any ecosystem because they produce organic matter from inorganic substances, providing the energy base for all other organisms.