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
X-ray feature of pyloric stenosis is – 
Select and explain. 
A. Single bubble appearance, B. Double bubble appearance, C. Triple bubble appearance, D. Multiple air fluid levels
A: Single bubble appearance
Answer: A: Single bubble appearance 
Explanation: Single bubble appearance is seen in congenital hypertrophic pyloric stenosis.