This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Radiography, Subject name: Radiology
[{'content': 'Which of the following is seen in carcinoma oesophagus - \nSelect and explain. \nA. Rat tail appearance, B. Corkscrew appearance, C. Bird beak sign, D. Caterpillar sign', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., Rat tail appearance Rat tail appearance of esophagusEsophageal carcinomaMegaesophagus (sigmoid esophagus)"Bird beak" appearance Hurst phenomenon Achalasia cardiaYo-Yo motion of barium"Corkscrew" appearance (esophageal curling)Rosary-bead\'sheikh kebab configurationChain of bead appearance Diffuse esophageal spasm', 'role': 'assistant'}]