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.

the answer is c i did the same question so i know that's right!

dopamine..

"it was found that some people who were taking the drug l-dopa to raise their levels of dopamine were developing schizophrenic-like symptoms supporting research a strength of the dopamine hypothesis is that there are many studies which have shown support for the neurochemical explanation."