What Free-Living Organisms Developed into Both Mitochondria and Chloroplasts

Question

What free-living organisms developed into both mitochondria and chloroplasts?
A) protists
B) animals
C) bacteria
D) plants

Accepted Answer

Mitochondria and chloroplasts are believed to have evolved through endosymbiosis, where an organism lives inside another organism and eventually evolves to become an organelle. In this case, the ancestral organism that gave rise to mitochondria and chloroplasts was likely a free-living prokaryotic bacterium.