When a gene is found on a sex chromosome, it is said to be sex-linked. Because males and females have different combinations of sex chromosomes, the ratio of inheritance for a sex-linked gene can be different between men and women. In mammals, females are homogametic, which means they have two copies of the same chromosome (the X-chromosome). Males are heterogametic, having only one copy of the X-chromosome.
Which of the following scenarios gives both sons and daughters the SAME probability of being born with a disease?
A. The disease is X-linked dominant. A heterozygous mother is crossed with a father with the disease.
B. The disease is X-linked recessive. A heterozygous mother is crossed with a healthy father.
C. The disease is X-linked dominant. A heterozygous mother is crossed with a healthy father.
D. The disease is X-linked recessive. A mother with the disease is crossed with a healthy father.