Why is color-blindness more common in males than in females?

Why is color-blindness more common in males than in females?
  a. Because females would have to receive one copy of the recessive color blindness gene to
  actually express the trait.
  b. Because a male only needs to receive the recessive gene from his mother to be color-blind.
  c. Because color-blindness is an Y-linked trait.
  d. Females are hemizygous
  e. Males are never hemizygous

Question 2

The sex of a human is determined by:
  a. the number of chromosomes.
  b. the number of autosomes.
  c. the presence of only one X chromosome.
  d. the number of sex chromosomes.
  e. the presence of a Y chromosome