This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Peritoneum & GI Tract, Subject name: Anatomy
[{'content': 'Length of lower esophageal sphincter - \nSelect and explain. \nA. 1-2 cm, B. 3-4cm, C. 1-2 mm, D. 3-4 mm', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is \'b\' i.e., 3-4 cm "The cricopharyngeal sphincter is 2-3 cm, and the lower esophageal sphincter (LES) is 3-4 cm long". - Textbook of GI Surgeryo Approximately 2 cm of the esophagus lie below the diaphragm in the abdomen (abdominal part of esophagus)o Within this portion of esophagus the abdominal part of LES is locatedo Another 1-2 cm of LES lie above the diaphragm in mediastinum, i.e. thoracic part of LES.o Thus total length of LES is 3-4 cm.', 'role': 'assistant'}]