Henry Goddard Studied Five Generations of Offspring of Martin Kallikak

Henry Goddard studied five generations of offspring of Martin Kallikak (a pseudonym) , a soldier of the American Revolution. Some of the descendants were the product of a liaison with a retarded tavern maid while some resulted from Kallikak's marriage to a respectful woman of normal intelligence. What did Goddard conclude from his research?

A) There were few differences in the achievements between the two lines of descendants; this led Goddard to conclude that mothers contributed little genetic material to their offspring.
B) There were large differences in the accomplishments of the two groups, which Goddard attributed to the genetic makeup of Kallikak's two mates.
C) There were few differences in the achievements between the two lines of descendants; this led Goddard to conclude that Intellectual disability is not inherited.
D) There were large differences in the accomplishments of the two groups, which Goddard attributed to the childrearing strategies of Kallikak's two mates.