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': 'Which does not take pa in formation of right subclan aery ? \nSelect and explain. \nA. 2nd arch aery, B. 4th arch aery, C. 7th arch aery, D. All three take pa', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., 2nd arch aery", 'role': 'assistant'}]