According to the endosymbiosis theory, how many membranes should a mitochondrion have

The endosymbiotic theory is described that the the primitive eukaryotic cell has ingested a prokaryote to become the mitochondria and the chloroplast. The mitochondria is actually a primitive prokaryote capable of performing cellular respiration. According to this theory, the mitochondria (coming from a primitive prokaryote) must have two membranes, an inner membrane and an outer membrane. 

Chloroplasts also have two cell membranes. 

According to the endosymbiosis theory, a mitochondrion shouldhave two membanes. Endosymbiotic theory is a theory that explains how eukaryotic cells may have evolved from prokaryotic cells. The theory deals with the origins of mitochondria and chloroplast, two eukaryotic organelles that have bacteria characteristics. These organelles are believed to have developed from symbiotic bacteria. According to this theory the mitochondria has two membranes; the outer membrane and the innermembrane.

C) reflection (i also looked up the other choices just to make sure)