Climate changes thats what im guessing .. not too sure though ... sorry
i believe that it is chromosomes
(D) Both perform photosynthesis is the observation that led researchers to propose that chloroplasts evolved from cyanobacteria.
Chloroplasts is the area where photosynthesis takes place. It is a green organelle in a plant cell. Pigments called the chloros in a chlorophyll are needed for the photosynthesis.
Cyanobacteria or blue-gree algae contains a blue photosynthetic pigment and a chlorophyll for photosynthesis.