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: Surgery
In congenital pyloric stenosis the defect usually lies in - antrum - 
Select and explain. 
A. Nerve fibres, B. Circular muscle fibres, C. Longitudinal muscle fibres, D. Mucosa
B: Circular muscle fibres
Answer: B: Circular muscle fibres 
Explanation: None