## **Core Concept**
The question tests the understanding of neonatal intestinal obstruction causes and their characteristic radiological findings. Intestinal obstruction in newborns can be due to various causes, including mechanical and functional issues. The presence of multiple air-fluid levels on an abdominal X-ray is indicative of a mechanical obstruction.

## **Why the Correct Answer is Right**
The correct answer, **D. Jejunal atresia**, is a condition characterized by a congenital obstruction of the jejunum, which is a part of the small intestine. This condition leads to a mechanical obstruction, preventing the normal passage of intestinal contents. On an abdominal X-ray, multiple air-fluid levels are seen because gas and fluid accumulate in the obstructed segments of the intestine. Jejunal atresia typically presents with multiple air-fluid levels on X-ray due to the presence of gas in the stomach, duodenum, and multiple segments of the jejunum.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While duodenal atresia is a cause of neonatal intestinal obstruction, it typically presents with a "double bubble" sign on X-ray, showing gas in the stomach and duodenum but not multiple air-fluid levels throughout the intestine.
- **Option B:** Pyloric stenosis usually presents with gastric distension and a single bubble sign on X-ray, without multiple air-fluid levels, as the obstruction is at the pyloric level.
- **Option C:** Ileal atresia can present with multiple air-fluid levels but typically has fewer levels compared to jejunal atresia because the obstruction is more distal.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the presence of multiple air-fluid levels on an abdominal X-ray in a newborn with intestinal obstruction strongly suggests a distal intestinal obstruction, such as jejunal or ileal atresia. Jejunal atresia often presents with more pronounced symptoms and more air-fluid levels on X-ray compared to ileal atresia.

## **Correct Answer:** D. Jejunal atresia