**Core Concept**
Active management of the third stage of labor is a crucial obstetric practice that involves a series of steps to prevent postpartum hemorrhage (PPH) and other complications. It involves administration of uterotonic agents, controlled cord traction, and uterine massage to promote uterine contraction and minimize blood loss.

**Why the Correct Answer is Right**
Active management of the third stage of labor is most helpful in the prevention of postpartum hemorrhage (PPH). The administration of uterotonic agents such as oxytocin or ergotamines stimulates uterine contractions, which helps to reduce bleeding. Controlled cord traction and uterine massage also aid in promoting uterine contraction and minimizing blood loss. This multi-faceted approach is essential in preventing PPH, which is a leading cause of maternal mortality worldwide.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while it is true that active management of the third stage of labor can prevent PPH, it is not the only condition that it can prevent. Other conditions, such as infection and retained placenta, are not directly related to the active management of the third stage of labor.
**Option B:** This option is incorrect because while it is true that active management of the third stage of labor can prevent PPH, it is not the most effective method of prevention. Other methods, such as antenatal uterotonic agents and cesarean section, may also be effective in preventing PPH.
**Option C:** This option is incorrect because while it is true that active management of the third stage of labor can prevent PPH, it is not the most immediate cause of PPH. Other factors, such as uterine atony and retained placenta, are more direct causes of PPH.

**Clinical Pearl / High-Yield Fact**
The key to successful active management of the third stage of labor is prompt administration of uterotonic agents, controlled cord traction, and uterine massage. This multi-faceted approach can significantly reduce the risk of PPH and other complications.

**Correct Answer:** D. Postpartum Hemorrhage