How do autotrophs and heterotrophs benefit one another within an ecosystem?

A.
Autotrophs synthesize ATP and other nutrients for heterotrophs, which produce oxygen for autotrophs.
B.
Autotrophs produce oxygen and carbon dioxide for heterotrophs, which produce chemical energy for autotrophs.
C.
Autotrophs fix carbon and produce oxygen for heterotrophs, which produce carbon dioxide for autotrophs.
D.
Autotrophs transform chemical energy into radiant energy for heterotrophs, which fix carbon for autotrophs.