## Core Concept
The question pertains to the characteristics and functions of placental hormones, which are crucial for maintaining pregnancy and fetal development. These hormones are produced by the placenta and have various effects on the mother's body and fetal growth.

## Why the Correct Answer is Right
Human chorionic gonadotropin (hCG) is a key placental hormone that maintains the corpus luteum during early pregnancy, ensuring continued production of progesterone. This hormone is produced by the syncytiotrophoblast cells of the placenta. Its role is critical in the initial stages of pregnancy.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, incorrect options might include statements that are not accurate regarding the function, production, or role of placental hormones like hCG, human placental lactogen (hPL), or others.
- **Option B:** Similarly, without the content, it's assumed that any incorrect statement about placental hormones, such as their function or regulation, would be wrong.
- **Option D:** Again, lacking the specific details, any statement contradicting established knowledge on placental hormones and their roles would be incorrect.

## Clinical Pearl / High-Yield Fact
A crucial point to remember is that **hCG levels** are often used as a marker for pregnancy and can be detected in blood and urine. They are vital for the maintenance of the corpus luteum and, consequently, progesterone production during early pregnancy. A decline or abnormal levels can indicate potential issues.

## Correct Answer: C.