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': 'One of the following mutation is potentially lethal \nSelect and explain. \nA. Substitution of adenine for cytosine, B. Substitution of methylcytosine for cytosine, C. Substitution of guanine for cytosine, D. Insertion of one base', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Insertion of one base causes frame shift mutation. This result in production of garbled protein (protein with completely different AA sequence). So, this can be lethal.', 'role': 'assistant'}]