Tay-Sachs disease is a genetic disorder that is usually fatal in young children. If both parents are carriers of the disease, the probability that their offspring will develop the disease is approximately .25. Suppose a husband and wife are both carriers of the disease and the wife is pregnant on three different occasions. If the occurrence of Tay-Sachs in any one offspring is independent of the occurrence in any other, what are the probabilities of these events?
a. All three children will develop Tay-Sachs disease.
b. Only one child will develop Tay-Sachs disease.
c. The third child will develop Tay-Sachs disease, given that the first two did not.