This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Guanidine special group is presesnt in \nSelect and explain. \nA. Arginine, B. Proline, C. Tryptophan, D. Tyrosine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: AMINO ACID SPECIAL GROUP Arginine Guanidinium Proline Pyrolidine Tryptophan Indole Phenylalanine Benzene Tyrosine Phenol Histidine Imidazole Methionine Thioether linkage Reference: Harpers illustrated biochemistry 30th edition', 'role': 'assistant'}]