A Dog Breeder Wishes to Develop a Breed That Does

A dog breeder wishes to develop a breed that does not bark. She starts with a diverse mixture of dogs. Generation after generation, she allows only the quietest dogs to breed. After 30 years of work she has a new breed of dog with interesting traits, but on average, the dogs still bark at about the same rate as other dog breeds. Which of the following would be a logical explanation for her failure?

A) There is a great deal of variation for the trait (barking) .
B) The tendency to bark is not a heritable trait.
C) The selection was artificial, not natural, so it did not produce evolutionary change.
D) Quiet dogs have fewer pups than barkers.