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
[{'content': 'Cervical oesophagus corresponds to \nSelect and explain. \nA. C3 C4 C5, B. C2 C3, C. C5 C6 C7, D. C7 C8', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cervical esophagus stas at inferior margin of cricoid cailage that corresponds to corpus of 6th cervical veebra. This level is marked by a carotid tubercula named "Chasseing tubercula," which is an impoant landmark in cervical esophagectomy. Cervical esophagus ends at inferior edge of first dorsal veebra that comes up to a horizontal plane of jugular incisura of sternum. The endpoint is the staing point of upper mediastinum, and from this point it is thoracic esophagus. Cervical esophagus is 5-6 cm long, and its luminal diameter is 1.4-1.5 cm at its narrowest point. Ref -<a href="', 'role': 'assistant'}]