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: Physiology
[{'content': 'Pacemaker cells are absent in \nSelect and explain. \nA. Colon, B. Esophagus, C. Stomach, D. Small intestine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pacemaker cells are absent in esophagus and proximal part of atomach.', 'role': 'assistant'}]