**Core Concept**
Intestinal obstruction in newborns is a serious condition that requires prompt diagnosis and treatment. The presence of multiple air fluid levels on abdominal X-ray is a classic sign of intestinal obstruction, which occurs when there is a blockage in the normal flow of intestinal contents.

**Why the Correct Answer is Right**
Newborn intestinal obstruction is often caused by conditions such as volvulus, intussusception, or meconium ileus. Volvulus is a twisting of the intestine that can lead to obstruction and ischemia. Intussusception is a condition where one part of the intestine slides into another, causing obstruction. Meconium ileus is a condition where the meconium is thick and sticky, causing an obstruction in the small intestine. The presence of multiple air fluid levels on abdominal X-ray is a sign of intestinal obstruction, and the correct diagnosis would depend on the specific clinical presentation and imaging findings.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because pyloric stenosis typically presents with projectile vomiting and a palpable pyloric mass, rather than intestinal obstruction with multiple air fluid levels.
**Option B:** This option is incorrect because Hirschsprung's disease typically presents with a history of constipation and a failure to pass meconium in the first 48 hours of life, rather than intestinal obstruction with multiple air fluid levels.
**Option C:** This option is incorrect because gastrochisis typically presents with a rash-like skin defect and a protrusion of the intestine through the defect, rather than intestinal obstruction with multiple air fluid levels.

**Clinical Pearl / High-Yield Fact**
In newborns, the most common causes of intestinal obstruction are volvulus, intussusception, and meconium ileus. These conditions can be diagnosed with abdominal X-ray and require prompt surgical intervention to prevent complications.

**Correct Answer: A. Pyloric stenosis.**