9. Which one of the following descriptions about mutations is WRONG? (A) An adenosine replaced by a cytidine is a "transversion" mutation. (B) An adenosine replaced by a guanosine is a "transition" mutation. (C) A nonsense mutation results in a different amino acid being inserted in the protein. (D) Silent mutation means a change at the DNA level that does not result in any change of amino acid in the encoded protein.