<prompt> A 2-month-old, breastfed baby that was normal at bih begins to develop GI problems and cirrhosis of the liver. Molecular analysis indicates a normal amount of galactose-1-phosphate uridyl transferase GALT mRNA, but no observable enzyme activity. Which of the following would be the best possible explanation for this?Gene deletionNonsense mutationPremature transcription termination sequence in the DNAPromoter mutation  <response>: Nonsense mutation 