**Core Concept**
The process of placental separation is a critical step in stage 3 of labor, also known as the placental stage. This stage begins after the delivery of the fetus and ends with the delivery of the placenta. **Placental separation** is facilitated by the **uterine contractions** that help in shearing the placenta from the uterine wall.

**Why the Correct Answer is Right**
Although the exact answer choice is not provided, a key sign of placental separation is the **gush of blood** from the vagina as the placenta separates, followed by the placenta's descent into the lower uterine segment or vagina. Another indicator is the **lengthening of the umbilical cord** as the placenta moves downward.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific details, it's hard to pinpoint why each option might be incorrect, but generally, signs that are not directly related to the physical separation or movement of the placenta would be incorrect.
**Option B:** Similarly, without specifics, any option not directly indicating placental movement or separation would be incorrect.
**Option C:** This would be incorrect if it does not accurately describe a direct sign of placental separation.
**Option D:** This option would be wrong if it refers to a symptom or sign not uniquely associated with the separation of the placenta.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **vaginal bleeding** increases as the placenta separates due to the loss of the placenta's attachment to the uterus, and this can be a critical indicator of the process.

**Correct Answer:** Unfortunately, without the specific answer choices provided, it's not possible to give a precise correct answer line. Normally, it would follow the format: **Correct Answer: [Letter]. [Answer Text]**