6. Select the scenario in which a mutation may become fixed in a population.
A mutation causing light skin shows up in a population of people living near the equator in South America.
A mutation for a stubby tail occurs in a population of Eastern gray squirrels, which normally have long, bushy tails.
Several bacteria in a population resistant to the antibiotic erythromycin show susceptibility to erythromycin because of a recent mutation.
A mutation occurs in a population of brown toads, causing green stripes that allow for better camouflaging in its habitat.
In a population of people whose main food source is the milk of their livestock, a mutation for lactose intolerance appears.