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: Biochemistry
[{'content': 'Guanidine group is present in \nSelect and explain. \nA. Histidine, B. Proline, C. Tryptophan, D. Arginine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Amino acid\xa0\xa0\nSpecial group\n\n\n\n\n\n\n\n\nHistidine\n\n\nImidazole\n\n\n\n\nProline\n\n\nImino group / Pyrrolidine group\n\n\n\n\nTryptophan\n\n\nIndole\n\n\n\n\nariginine\n\n\nGuanidine group\n\n\n\n\nPhenylalanine\n\n\nBenzene ring\n\n\n\n\nTyrosine\n\n\nPhenol.', 'role': 'assistant'}]