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
Base substitution mutations can have be following molecular consequence except: 
Select and explain. 
A. 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
C: Reading frame changes downstream to the mutant site
Answer: C: Reading frame changes downstream to the mutant site 
Explanation: C i.e. Reading frame changes down stream to the mutant site