If both the mother and the father are carriers for the cystic fibrosis gene, what are the chances that their child will be a cystic fibrosis carrier?

a. 0%
b. 25%
c. 50%
d. 75%

C
As shown in Figure 15-2, if this couple had four children, the odds are that one would have cystic fibrosis (1 in 4 chance, 25%), two would be carriers (2 in 4 chance, 50%), and one would not be a carrier (1 in 4 chance, 25%).