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': 'Base substitution mutations can have the following molecular consequence except \nSelect and explain. \nA. Changes one codon for an amino acid into another codon for that same amino acid, B. Codon for one amino acid is changed into a codon of another amino acid, C. Reading frame changes downstream to the mutant site, D. Codon for one amino acid is changed into a translation termination codon', 'role': 'user'}, {'content': "Answer: C \nExplanation: Option 'a' is silent mutation, option 'b' is missense mutation, and option 'd' is nonsense mutation. All three are types of point mutation (base substitution mutation). Option 'c' is frame-shift mutation.", 'role': 'assistant'}]