This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Double bubble sign is a radiological feature of: 
Select and explain. 
A. Pyloric stenosis, B. Duodenal atresia, C. Hirschsprung's disease, D. Necrotising enterocolitis
B: Duodenal atresia
Answer: B: Duodenal atresia 
Explanation: Ans. Duodenal atresia