A scientist is studying endosymbiosis in cells. This means she is investigating
A. how mitochondria and chloroplasts were derived from eukaryotic cells.
B. how mitochondria and chloroplasts were derived from prokaryotic cells.
C. how mitochondria and chloroplasts evolved into eukaryotic cells.
D. how mitochondria and chloroplasts evolved into prokaryotic cells.
E. how mitochondria but not chloroplasts evolved into prokaryotic cells.
Answer: B