This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
What is the length of the lower esophageal sphincter? 
Select and explain. 
A. l-2cm, B. 3-5 cm, C. 0.5-0.8cm, D. 7-10cm
B: 3-5 cm
Answer: B: 3-5 cm 
Explanation: Ans. is 'b' i.e., 3-5 cm [Ref: McGraw-Hill Concise Dictionary of Modem Medicine. 2002 by The McGraw-Hill Companies, Inc.)* Lower esophageal sphincter is a zone of 3-5 cm located at the junction of the distal esophagus and gastric cardia acting as a physical barrier in preventing gastric reflux.