**Core Concept**
The placenta produces various hormones crucial for maintaining pregnancy. These hormones include **human chorionic gonadotropin (hCG)**, **estrogen**, **human placental lactogen (hPL)**, and others that support fetal development and maternal adaptation.

**Why the Correct Answer is Right**
**hCG** is produced exclusively by the placenta, specifically by the syncytiotrophoblast cells, and plays a key role in maintaining the corpus luteum during early pregnancy. **hPL** is also exclusively produced by the placenta and helps in maternal glucose and lipid metabolism, ensuring the fetus receives adequate nutrition.

**Why Each Wrong Option is Incorrect**
**Option B:** Estrogen is not exclusive to the placenta as it is also produced by the ovaries and adipose tissue.
**Option D:** Prolactin (PRL) is primarily produced by the pituitary gland, not exclusively by the placenta.

**Clinical Pearl / High-Yield Fact**
Remember that **hCG** and **hPL** are placental hormones, while **estrogen** and **prolactin** have broader sources, including non-placental tissues.

**Correct Answer:** A. hCG