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
Which of the following is not a semi synthetic Pencillin 
Select and explain. 
A. Pencillin V, B. Pencillin G, C. Methicillin, D. Amoxicillin
B: Pencillin G
Answer: B: Pencillin G 
Explanation: Refer GG1477. Pencillin G is natural pencillin all other are semisynthetic