Duchenne muscular dystrophy is an X-linked recessive disorder.

A Punnett square is shown. The columns are labeled Upper X m and Upper Y. The rows are labeled x Upper M and x m.

What is the probability that a female offspring of the cross that is shown above would have a recessive allele for Duchenne muscular dystrophy disorder?
0 percent
25 percent
50 percent
100 percent