This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
[{'content': 'Surface anatomy for internal jugular vein \nSelect and explain. \nA. Ear lobule to medial third of clavicle, B. Ear lobule to middle third of clavicle, C. Ear lobule to lateral third of clavicle, D. Mastoid to third of clavicle', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Internal jugular vein is marked by a broad line by joining these two points: a.The first point on the neck medial to the lobule of the ear b.The second point at the medial end of the clavicle. <img src=" /> Ref.BDC volume 3,sixth edition pg 303', 'role': 'assistant'}]