Mitochondria and chloroplasts are structures found in the eukaryotic cells.
What is the theory regarding their origins?

(Choice A)
A
They developed as a prokaryotic cell membrane folded in on itself.

(Choice B)
B
They were non-living food particles that were ingested by bacteria.

(Choice C)
C
They developed from prokaryotic cells that were engulfed by the other cells.

(Choice D)
D
They originated from photosynthetic bacteria.