Which of the following statements is false about human chorionic gonadotropin?

Which of the following statements is false about
  human chorionic gonadotropin?
  a. It is initially secreted by the blastocyst.
  b. It stimulates the corpus luteum to continue
  secreting progesterone and estrogens.
  c. Once it forms, the placenta secretes the
  hormone.
  d. It prevents the uterine lining from sloughing off.
  e. The earliest it can be detected in the urine is
  seven weeks after conception.

Question 2

The extra-embryonic membrane that forms the
  majority of the placenta is the
  a. amnion.
  b. allantois.
  c. chorion.
  d. yolk sac.
  e. umbilical cord.