Hip Dysplasia Is a Common Ailment in Large Dog Breeds

Hip dysplasia is a common ailment in large dog breeds including Rottweilers in the United States. One breeder decides to import several females from Germany where the disease is less common to mate with his male dogs. This introduction of new alleles into his dog population is an example of __________.

A) natural selection
B) adaptation
C) gene flow
D) dispersal