What is the answer with explaining

After which event could you say that evolution has occurred? question 1 options: an allele frequency changes in a population. a white-eyed fly is born into a population of brown-eyed flies. a new predator comes into an environment. an animal gets fat.

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

The function of the excretory system is to control homeostasis and