In a normal pregnant woman,the amount of total gonadotropin activity was assessed. The result expected was

• A
  high level of circulating $FSH$ and $LH$ in the uterus to stimulate implantation of the embryo
• B
  high level of circulating $hCG$ to stimulate endometrial thickening
• C
  high levels of $FSH$ and $LH$ in uterus to stimulate endometrial thickening
• D
  high level of circulating $hCG$ to stimulate estrogen and progesterone synthesis.