This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Radiology
Bird beak appearance on X-ray is a feature of- 
Select and explain. 
A. Achlasia cardia, B. Carcinoma esophagus, C. Hiatus hernia, D. Diffuse esophageal spasm
A: Achlasia cardia
Answer: A: Achlasia cardia 
Explanation: Ans. is 'a' i.e., Achlasia cardia * "Bird beak appearance on barium study is seen in achlasia cardia.Important esophageal signs on radiographySignConditionRat tail appearance of esophagusEsophageal carcinomaMega-esophagus (sigmoid esophagus)"Bird beak" appearanceHurst phenomenonAchlasia cardiaYo-Yo motion of barium"Corkscrew" appearance (esophageal curling)Rosary-bead/sheikh kebab configurationChain of bead appearanceDiffuse esophageal spasm