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
Radiologic feature suggestive of Achalasia cardia is- 
Select and explain. 
A. Absence of gastric air bubble, B. Air fluid level in mediastinum, C. Sigmoid ecophagus, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None