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': 'The vein formed by union of posterior division of retromandibular vein and posterior auricular vein is \nSelect and explain. \nA. Common facial vein, B. Anterior jugular vein, C. External jugular vein, D. Interior jugular vein', 'role': 'user'}, {'content': 'Answer: C \nExplanation: External jugular vein is formed by posterior auricular vein and posterior division of retromandibular vein.', 'role': 'assistant'}]