16. Some heterokonts (stramenophiles) are photosynthetic and gained their chloroplasts by:(A) primary endosymbiosis with a photosynthetic cyanobacterium.(B) primary endosymbiosis with a photosynthetic glaucophyte chloroplast.(C) secondary endosymbiosis with a green alga.(D) secondary endosymbiosis with a red alga.(E) secondary endosymbiosis with a dinoflagellate.