What determines the development of male or female sex organs in the human embryo?

What determines the development of male or female sex organs in the human embryo?
 
  a. environmental factors
  b. genes on the X chromosome
  c. genes on the Y chromosome
  d. genes on both the X and Y chromosomes
  e. neither the X or the Y chromosomes

Question 2

In the postpartum female,
 
  a. oxytocin stimulates the production and secretion of milk.
  b. oxytocin stimulates the production of milk and prolactin stimulates the secretion of milk.
  c. prolactin stimulates the production and secretion of milk.
  d. prolactin stimulates the production of milk and oxytocin stimulates the secretion of milk.
  e. estrogen and progesterone are directly responsible for the production and secretion of
  milk.