**Core Concept**
Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality, often managed with uterotonic agents that stimulate the uterus to contract. **Uterotonic agents** such as oxytocin, methylergonovine, and carboprost tromethamine are commonly used.

**Why the Correct Answer is Right**
The correct answer is based on the understanding of which drugs are typically used in PPH management. Oxytocin is a first-line treatment due to its rapid onset of action, while methylergonovine and carboprost tromethamine are used when oxytocin is ineffective or contraindicated.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because oxytocin is a primary uterotonic agent used.
**Option B:** Incorrect as methylergonovine is also used for PPH.
**Option C:** Incorrect because carboprost tromethamine, a prostaglandin analogue, is used in PPH management.

**Clinical Pearl / High-Yield Fact**
A key point in managing PPH is the prompt administration of uterotonic agents to prevent severe blood loss.

**Correct Answer:** D.