The Endosymbiotic Theory States That Mitochondria Originated from

The endosymbiotic theory states that mitochondria originated from

A) a routine step in evolution.
B) the fusion of several prokaryotes.
C) purple bacteria entering and remaining in the cytoplasm of another cell.
D) the slow evolution of various organelles over millions of years, particularly during the time of the dinosaurs.
E) a long, intense period of lightning.