Ans. is 'b' i.e., 9 weeks o Maximum levels of beta HCG occur on 66th day of pregnancy, i.e. 9 weeks 3 days.Human Chorionic Gonadotropino Produced almost exclusively in placenta, low levels in fetal kidneyo Molecular weight - 36000 - 40000 Da.o Highest carbohydrate content of any hormone - 30 percent.o It has a long half life - 36 hours as against only 2 hours of LH; as the carbohydrate component, and especially the terminal sialic acid, protects the molecule from catabolismo Alpha subunit of LH, FSH, TSH and HCG are structurally related to each other. Recombination of alpha and beta subunits of these four hormones gives a molecule with biological activity characteristic of the hormone from which the beta subunit was derivedo Principal form in plasma - Intact hCGo Principal form in urine - beta core fragment (terminal hCG degradation product).Functionsa) Maintainence of corpus luteum till 6 weeks of pregnancy.b) Stimulation of fetal testicular testosterone secretion which is maximum approximately when hCG levels peak. Thus at a critical time in male sexual differentiation, hCG enters fetal plasma from the syncytiotrophoblast. In the fetus, it acts as an LH surrogate to stimulate Leydig cell replication and testosterone synthesis to promote male sexual differentiation. Before approximately 110 days, there is no vascularization of the fetal anterior pituitary from the hypothalamus. Thus, pituitary LH secretion is minimal,and hCG acts as LH before this time. Thereafter as hCG levels fall, pituitary LH maintains modest testicular stimulation.c) Immunosuppressive activity, inhibits maternal processes of immunorejection of the fetus as a homograft.d) Stimulates maternal thyroid (thyrotropic action).e) Promotes relaxin secretion from corpus luteum.o Choriocarcinoma is associated with increased secretion of beta - hCG that is glycosylated to a greater degree, so called hyperglycosylated hCG, sometimes called invasive trophoblast antigen.