Which statement best describes a keystone species? A. Its birthrate is the highest of all the species in the community. B. It has the highest amount of genetic diversity in the community. C. Its extinction would cause a significant change in the community. D. It serves as a predator of many other species in the community.

answer: the correct answer for the fill in the blank is rods.

rods are the specialized photoreceptor cells that are present in the retina of human eye. they are responsible for vision in the night time ( also called scotopic vision). they have very low visual acuity and color distinguishing ability.

as they are responsible for vision in night time, therefore they are found predominantly in the nocturnal animals.