**Core Concept**
Placenta previa is a pregnancy complication characterized by the placenta partially or completely covering the internal cervical os. This condition can lead to severe bleeding, which may necessitate immediate delivery. The underlying issue is the abnormal implantation of the placenta, which can compromise the integrity of the uterine lining and lead to hemorrhage.

**Why the Correct Answer is Right**
The correct answer involves understanding the clinical presentation and management of placenta previa. In this condition, the placenta is positioned such that it may separate from the uterus during pregnancy or labor, resulting in significant blood loss. This can be life-threatening for both the mother and the fetus. The primary concern is the risk of antepartum hemorrhage, which may necessitate immediate delivery, often by cesarean section. The management of placenta previa involves close monitoring of the mother and the fetus, with a focus on preventing and managing bleeding.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the clinical presentation of placenta previa. While bleeding is a significant concern, it is not the only symptom associated with this condition.
**Option B:** This option is incorrect because it does not accurately describe the management of placenta previa. While bed rest may be recommended, it is not the primary treatment for this condition.
**Option C:** This option is incorrect because it does not accurately describe the pathophysiology of placenta previa. The condition is not caused by a deficiency in uterine tone.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that placenta previa is a condition that requires immediate attention if bleeding occurs. The classic teaching is that "pain is not a symptom of placenta previa, but bleeding is." This highlights the importance of vigilance in monitoring for signs of antepartum hemorrhage.

**Correct Answer:** C.