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 of the following muscle is responsible for facial expression during smiling? \nSelect and explain. \nA. Zygomaticus major, B. Levator labii superioris, C. Levator anguli oris, D. Procerus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]