A woman heterozygous for color blindness (an X-linked recessive allele) marries a man with normal ...

A woman heterozygous for color blindness (an
  X-linked recessive allele) marries a man with
  normal color vision. What is the probability
  that their first child will be color blind?
  a. 25
  b. 50
  c. 75
  d. 100
  e. none of these

Question 2

Males tend to be affected in greater numbers
  by X-linked recessive genetic disorders than
  are females because
  a. females have two dominant genes for the
  disorder.
  b. males have only one X chromosome.
  c. males have a double dose of the gene.
  d. Y chromosomes are not as strong as X
  chromosomes.
  e. none of these