**Core Concept**
Beta HCG (human chorionic gonadotropin) is a hormone produced during pregnancy that is crucial for maintaining the corpus luteum and supporting embryonic development. It is a glycoprotein hormone produced by the placenta.

**Why the Correct Answer is Right**
Beta HCG is secreted by the syncytiotrophoblast, a layer of cells that forms the outer layer of the developing embryo. The syncytiotrophoblast produces Beta HCG, which is essential for maintaining the corpus luteum, thus supporting the continuation of pregnancy. This hormone also plays a role in implantation of the embryo and embryonic development.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because Beta HCG is not secreted by the ovaries, although they do produce other hormones essential for reproduction.
**Option B:** Incorrect because the pituitary gland produces other hormones that regulate various bodily functions, but it does not produce Beta HCG.
**Option C:** Incorrect because the placenta is the site of production, but it is the syncytiotrophoblast layer of cells that actually secretes Beta HCG.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that Beta HCG levels are used as a marker for pregnancy and can be used to monitor the health of the pregnancy. Abnormal levels of Beta HCG can indicate potential issues with the pregnancy, such as ectopic pregnancy or miscarriage.

**Correct Answer: C. Syncytiotrophoblast.**