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: Anatomy
[{'content': 'Esophagus starts at which level - \nSelect and explain. \nA. Upper border of cricoid cartilage, B. Lower border of cricoid cartilage, C. Thyroid cartilage, D. Hyoid cartilage', 'role': 'user'}, {'content': 'Answer: B \nExplanation: At the lower end of pharynx, at the level of lower border of cricoid cartilage, esophagus begins.', 'role': 'assistant'}]