There Are Two Competing Theories Put Forth to Explain the Origin

There are two competing theories put forth to explain the origin of eukaryotic cells. Which of the following CORRECTLY states one of these theories?

A) Ancient eukaryotic cells resembling archaeal cells acquired symbiotic bacteria that eventually took up permanent residence to become mitochondria.
B) Two types of prokaryotic cells, one of which was photosynthetic, fused to become the first ancient eukaryotic cell.
C) A symbiotic relationship between a cyanobacteria and an archaeon created the first ancient eukaryotic cell.
D) Ancient eukaryotic cells resembling archaeal cells acquired symbiotic cyanobacteria that eventually took up permanent residence to become chloroplasts.