If both parents are carriers for thalassemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child?

The correct option is 25. In autosomal recessive inheritance, both parents must carry one copy of the recessive gene (they are carriers) for their child to inherit the disorder. Each parent has a 50% chance of passing on the recessive gene. Therefore, the probability of a child inheriting the recessive gene from both parents is 0.5 * 0.5 = 0.25 or 25%.