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
Non visualization of gastric fundic bubble with air-fluid level in retrocardiac region suggests: September 20003 
Select and explain. 
A. Carcinoma esophagus, B. Esophageal web, C. Achalasia cardia, D. Congenital hyperophic pyloric stenosis
C: Achalasia cardia
Answer: C: Achalasia cardia 
Explanation: Ans. C i.e. Achalasia cardia