Cotton-topped tamarins are small primates with tufts of long white hair on their heads. While studying these creatures, a scientist noticed that males with longer hair get more opportunities to mate and that they father more offspring than males with shorter hair. Which of the following possible studies would be the best design for testing if longer hair is an adaptive trait? Assume that hair length is a trait that is inherited. a. Capture a group of males with long hair at random, and cut the hair very short in half of the males; then, compare the number of matings of males with their hair left unchanged vs. males with shortened hair.
b. From long-term observational records, determine the ages of males and then compare the number of matings by males of different ages.
c. Follow at least 20 troops of tamarins and compare the number of matings by males that live high in trees vs. those that live on the ground.
d. Follow at least ten troops of tamarins and compare the number of matings by males that live in large groups vs. those that live in small groups.