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': 'The lower esophageal sphincter (LES) resting pressure is: \nSelect and explain. \nA. 5-10 mm Hg, B. 10-15 mm Hg, C. 15-25 mm Hg, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The LES measures 3-4 cm in length and its resting pressure ranges between 15 and 24 mm Hg. At the time of swallowing, the LES relaxes for 5-10 seconds to allow the food bolus to enter the stomach, and then it regains its resting tone', 'role': 'assistant'}]