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 level of FSH and LH in uterus to stimulate endometrial thickening.

(d) High level of circulating hCG to stimulate estrogen and progesterone synthesis.