The endosymbiotic theory hypothesizes that mitochondria and chloroplasts were formed when <u>prokaryotic </u>cells were engulfed by larger cells that were precursors to <u>eukaryotic </u>cells.
prokaryotic ; eukaryotic
I believe your answer is B. Taxonomy
Transpiration should be your answer, hope I helped. Good luck with your future studies!!
-A
