The endosymbiont hypothesis introduced the idea, now supported by considerable experimental evidence, that
A. Eucaryotic cells evolved from procaryotic cells.
B. proteins synthesized on ribosomes attached to the surface of the endoplasmic reticulum travel to the Golgi apparatus before being shipped out to other destinations in the cell.
C. chloroplasts and mitochondria were once free-living procaryotic cells.
D. mitochondria have the ability to break down fuel molecules, releasing energy which can be converted into a source used by the cell to do work.
Answer: A