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': 'Most common muscle to be congenitally absent - \nSelect and explain. \nA. Teres major, B. Pectoralis major, C. Gastrosoleus, D. Semimembranosus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Congenital absence of Pectoralis major is the most common.', 'role': 'assistant'}]