A couple, both carriers of the gene sickle-cell anemia planning to get married, wants to know the chances of having anemic progeny

The correct option is D $25\%$
It is clear from the condition given that the parents are the carrier of the disease. Sickle-cell anemia is an autosomal linked recessive trait which gets transmitted from parents to offsprings when both the partners are the carrier for the gene. According to the situation given in the question, the cross is given below:


Thus, the chances of getting anemic progeny is only $25\%$ i.e. daughter will only be affected.