**Core Concept:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone that plays a crucial role in pregnancy, as it is produced by syncytiotrophoblast cells in the placenta.

**Why the Correct Answer is Right:** hCG is primarily secreted by the syncytiotrophoblast cells in the placenta. It plays a vital role in maintaining the corpus luteum function, which is necessary for maintaining the progesterone secretion that helps in maintaining the endometrial lining in preparation for implantation and embryonic development.

**Why Each Wrong Option is Incorrect:**

A. **False** - hCG is not secreted by the corpus luteum, but rather by the placenta during pregnancy.
B. **False** - Although luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are produced by the anterior and posterior pituitary glands, they are not the source of hCG.
C. **False** - hCG is not secreted by the ovaries, as it is produced by the placenta in pregnancy.
D. **False** - hCG is not secreted by the testes in males or the ovaries in females; it is produced by the placenta during pregnancy.

**Clinical Pearl / High-Yield Fact:** A high level of hCG in the blood during pregnancy is essential for monitoring the health of the gestation and detecting early miscarriages or ectopic pregnancies. It serves as a diagnostic marker for these conditions.