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
[{'content': "True about Schatzki\\'s ring:.a) Has skeletal muscleb) Causes dysphagiac) Contains all the layers of the esophagusd) Located at lower esophagus \nSelect and explain. \nA. c, B. bd, C. ab, D. ac", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]