A population of black cats has been interbreeding. However, in one litter, a sole gray kitten is born. The successive generations now have a few gray cats. Which mechanism is responsible for introducing this new allele in the cat population? A) Gene selection. B) Gene mutation. C) Gene flow. D) Genetic drift

The correct answer is B. Gene mutation

Since it would be almost impossible for a gray progeny to be created, this would classify as a gene mutation. Similar thing occurred with people who have blue and green eyes since once long ago only brown eyes existed, and the people who got blue eyes did so as a gene mutation.