The pedigree below tracks Duchenne Muscular Dystrophy (DMD) through several generations. DMD is an X-linked recessive trait.

If individuals I-1 and I-2 had another son, what is the chance that he would have DMD?

Choose 1

(choice A)
A
0%

(choice B)
B
25%

(choice C)
C
50%

(choice D)
D
100%

The image provided is not clear, however, the correct and clear image is attached with the

The correct answer is - 100 %

Explanation:

As we know DMD or Duchenne Muscular Dystrophy is a sex-linked recessive disorder and according to the given pedigree, it is clear that Individual I-1 is a normal male and 1-2 is a female who has two defective genes of the disorder as if she had only one defective gene she would have a carrier for the disorder.

All gametes produced by both male and female would be -

Male - X and Y

Female - Xd and Xd

Therefore all the male offsprings or son will get one defective gene Xh from the mother for sure and a Y chromosome from the father. All daughters will also carry one gene Xh that is defective from the mother and normal X from the father but would be carriers for the disorder.