The correct answer is A. Autotrophs fix carbon and produce oxygen for heterotrophs, which produce carbon dioxide for autotrophs.
Explanation:
In an ecosystem, autotrophs refer to organisms such as plants that produce their energy usually through photosynthesis and by using carbon fixation, this means they take carbon dioxide, sunlight, and water and transformed in glucose used for energy and glucose that is released. On the other hand, heterotrophs such as animals are organisms that need to feed on others to obtain nutrients and energy.
These organisms related to autotrophs because some of them feed on autotrophs such as rabbits feeding on grass. But besides this, heterotrophs use the oxygen released by autotrophs during respiration and produce carbon dioxide that is taken by autotrophs. Thus, autotrophs and heterotrophs benefit one another as "Autotrophs fix carbon and produce oxygen for heterotrophs, which produce carbon dioxide for autotrophs".
