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: Anatomy
Ilnd constriction in oesophagus is seen at the following site : 
Select and explain. 
A. Where it crosses left main bronchus, B. Crossing of aoa, C. At pharyngoesophageal junction, D. Where it pierces the diaphragm
B: Crossing of aoa
Answer: B: Crossing of aoa 
Explanation: B i.e. Crossing of Aoa