Oxygenic photosynthesis occurs in
a)	Chromatium	b)	Oscillatoria	c)	Rhodospirillum	d)	Chlorobium

(b)

Oscillatoria is a photosynthetic cyanobacterium. In this, photosynthesis water is electron donor and oxygen is a byproduct, i.e., oxygenic photosynthesis occurs. Rhodospirillum and Chlorobium are non-oxygenic photosynthetic, purple non-sulphur and green-sulphur bacteria.

Chromatium is purple sulphur bacterium and also non-oxygenic photosynthetic.