A mother is a carrier of an X-linked recessive disorder. The father is unaffected. What is the probability that a daughter will become a CARRIER?

Correct answer: D. 50%

• A. ❌ 25% is the probability for a son to be affected — not the carrier probability for daughters.
• B. ❌ 100% would require the father to also carry the X^a allele.
• C. ❌ 75% is not the correct probability for any of these outcomes.
• D. ✅ Correct. X-linked carrier mother (X^A X^a) × Normal father (X^A Y): Daughter genotypes: X^A X^A (normal, 50%) or X^A X^a (carrier, 50%). Therefore 50% of daughters will be CARRIERS.