What most likely brought about the formation of oxygen in the Earth's primitive atmosphere? 

A)  ozone producing prokaryotes 
B)  anaerobic prokaryotes 
C)  chemosynthetic bacteria 
D)  photosynthetic bacteria

Primitive Atmosphere

The early atmosphere of Earth, which was very different in composition from the current one, possibly composed of gases such as methane, ammonia, and water vapor.

Photosynthetic Bacteria

Bacteria that are capable of producing their own food through the process of photosynthesis.

Oxygen

A chemical element, represented by the symbol O, essential for life as it is a major component of air and water, supporting combustion and respiration.