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
A 40 year old female patient with dysphagia to both liquids and solids and regurgitation for 3 months. The dysphagia was non-progressive. What is the most likely diagnosis? 
Select and explain. 
A. Carcinoma of the esophagus, B. Lower oesophageal mucosal ring, C. Achalasia cardia, D. Reflux esophageal with esophageal stricture
C: Achalasia cardia
Answer: C: Achalasia cardia 
Explanation: Answer is C (Achalasia Cardia) Carcinoma Esophagus, lower esophagus ring and esophageal stricture are all associated with dysphagia for solids alone. Presence of dysphagia for both solids and liquids suggests a diagnosis of Achalasia cardia. Although dysphagia in Achalasia is progressive absence of progression does not exclude the diagnosis. Also amongst the options provided Achalasia is the single best answer of exclusion.