## Core Concept
Breech presentation refers to a situation where the fetus's buttocks or feet are positioned to be born first, rather than the head. This can be associated with various complications during delivery. The incidence of breech presentation varies depending on gestational age.

## Why the Correct Answer is Right
The correct answer indicates that approximately 3-4% of pregnancies are in breech presentation at term (around 37 weeks of gestation and beyond). This percentage is significant because breech presentations at term are associated with a higher risk of complications during delivery, such as umbilical cord prolapse, fetal distress, and birth trauma. The mechanism behind the increased risk involves the larger size of the fetal buttocks compared to the head, which can make delivery more challenging.

## Why Each Wrong Option is Incorrect
- **Option A:** 10-15% - This percentage is too high for the incidence of breech presentation at term. While breech presentation is more common earlier in pregnancy, many fetuses move to a cephalic (head-down) position as the pregnancy progresses.
- **Option B:** 20-25% - This is significantly higher than the actual incidence of breech presentation at term and likely overestimates the percentage earlier in pregnancy.
- **Option D:** 0.1-1% - This percentage is too low for the incidence of breech presentation at term, as it suggests a much rarer occurrence than what is clinically observed.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the majority of breech presentations at term are diagnosed prenatally through ultrasound. External cephalic version (ECV), a procedure where a healthcare provider attempts to manually turn the fetus to a cephalic position, is often considered for breech presentations at term to reduce the risk of complications associated with breech delivery.

## Correct Answer: C. 3-4%.