The endosymbiosis theory states the orgin of the eukaryotic cells began when

A. A mutation in prokaryotic cells led to the creation of new organelles

B. Prokaryotic cell consumed a smaller cell

C. Prokaryotic cells went extinct

D. A prokaryotic cell needed more energy and evolved a mitochondria

The correct answer is B. Prokaryotic cell consumed a smaller cell.

Explanation:

Endosymbiosis theory says that the origin of eukaryotic cell happens when a bigger prokaryotic cell consumer a smaller prokaryotic cell but the bigger cell did not consume the smaller cell rather these two cells remain in symbiotic association with each and later evolved as a eukaryotic cell.

The evidence of this theory can be seen in eukaryotic cells in the form of mitochondria and chloroplast in animal and plant cells. These two organelles are very closely related to today's prokaryotic cells.

Both the organelles have their own circular genome enclosed in double membranous structure and 70s ribosomes which resembles the bacterial cell. Therefore, the correct answer is B. Prokaryotic cell consumed a smaller cell.