This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
[{'content': 'Which of the following is not a semi synthetic Pencillin \nSelect and explain. \nA. Pencillin V, B. Pencillin G, C. Methicillin, D. Amoxicillin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer GG1477. Pencillin G is natural pencillin all other are semisynthetic', 'role': 'assistant'}]