If a man who has duchenne muscular dystrophy has kids with a woman who does not have or carry the allele, how many of their sons could have the disorder? a. none b. all

The answer is none. Since DMD is a recessive x-linked trait, the sons will receive the Y from the father, and an X from the mother. Since the mother does not have the disease and is not a carrier, the sons cannot get the recessive x.