Which of the following is the source of HCG in a pregnant female?

Human Chorionic Gonadotropin (hCG) is produced in syncytiotrophoblasts. This so-called pregnancy hormone is a glycoprotein with biological activity similar to luteinizing hormone (LH). Both act the plasma membrane LH-hCG receptor. Although hCG is produced almost exclusively in the placenta, it also is synthesized in fetal kidney. This hormone is structurally related to three other glycoprotein hormones--LH, FSH, and TSH. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 3. Implantation, Embryogenesis, and Placental Development. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.