This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gastrointestinal System Including Diarrhea, Subject name: Pediatrics
A 5-day-old term male neonate presents with delayed passage of meconium, abdominal distension and bilious vomiting. Barium enema and intestinal biopsy findings are shown below: What is the diagnosis? 
Select and explain. 
A. Congenital aganglionic megacolon, B. Hyperophic pyloric stenosis, C. Cystic fibrosis, D. Intestinal malrotation
A: Congenital aganglionic megacolon
Answer: A: Congenital aganglionic megacolon 
Explanation: 1st picture shows narrow distal segment with dilated proximal segment of intestine in Ba enema. 2nd picture shows hyperophied nerve bundles between muscular layer & submucosa and enteric nerve plexuses lacking ganglion cells in H&E stain. Both the above findings are suggestive of Hirschsprung disease (Congenital aganglionic megacolon)