The Amish population who migrated from Europe to the United States had very few individuals in their population. Additionally, their gene pool shows very few alleles due to inbreeding. A genetic trait called polydactyly (having six fingers), which is rare in other populations, is common amongst them. What kind of evolutionary effect is exhibited in this example? Select one of the options below as your answer:
a. Mutation
b. Natural selection
c. Founder effect