Each codon shown below specifies an amino acid. for which one is it possible that a change in a single base could create a stop codon? see section 16.3 ( page 342) .
AAA is the one that is possible that a change in a single base could create a stop in codonChanging the first base from A --> U creates the stop codon UAA. The answer in this question in which has a possible that change in a single base could create a stop codon is AAA.