Fill in the blank: Most organisms require that their internal environments remain in a fairly constant range, and so they maintain

A. Homeostasis

B. Metabolism

C. DNA

D. Stimulus

the correct answer is:

a population changes in response to a change in the environment.

the sun creates it's own light, also gives light and life to bunch of stuff like plants,animals,humans etc.photosyntesis is the process of making food which needs sun,water,nutrients etc.