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: Medicine
Endoscopy is contraindicated in 
Select and explain. 
A. Achalasia, B. Peptic stricture, C. Esophageal carcinoma, D. Esophageal web
A: Achalasia
Answer: A: Achalasia 
Explanation: Endoscopy is C/I in regurgitant lesions like Achalasia and Zenker's diverticulum as it carries the risk of rupture in mediastinum (Very risky).