This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Transition mutation of GATCCT is: (PGI Dec 2006) \nSelect and explain. \nA. GGTCCT, B. GTTCCT, C. GTCCCT, D. GGUGGT', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: A (GGTCCT) In Transition type of mutation, a purine base is replaced by another purine base (A-G) or a pyrimidine is replaced by another pyrimidine (C-T).So-Transition of -GATCCT is GGTCCT (only single base is changed, according to options given, it the only answer)', 'role': 'assistant'}]