The correct answer would be mitochondria or chloroplast.
Endosymbiosis refers to the evolution theory which explains the origin of eukaryotic cells from prokaryotic cells.
It is believed that cell organelles like chloroplast, mitochondria et cetera were free-living early prokaryotic cells which were taken inside the other cells by the process of endosymbiosis. It led to the origin of eukaryotic cells which were able to perform photosynthesis.
Thus, Keiko should mark chloroplast or mitochondria in the diagram.
Answer:a. A cataract is a clouding of the lens. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. The lens can be removed and replaced
B- Reproducing more often. If the environment is not right for them then reproduction doesn’t help them adapt. They respond by changing behavior, moving to another area, and even modifying their physical bodies (diets included).