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: ENT
[{'content': 'Intermittent dysphagia is caused by -a) Strictureb) Reflux esophagitisc) Achalasia cardiad) Pharyngeal diverticululame) Diffuse esophageal spasm \nSelect and explain. \nA. ab, B. bc, C. de, D. bd', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]