What single nucleotide change could produce variant 0011, SER549ILE?

More than 135 allele variants are listed from patients who have been diagnosed with cystic fibrosis (CF).  Of these, the most common is variant 0001, the in-frame three base deletion discussed in Chapter 10; this is abbreviated PHE508DEL to indicate the amino acid (PHE), the position (508), and the change in the gene (DEL). 

What single nucleotide change could produce variant 0011, SER549ILE?




Choice:
An insertion of a stop codon at position 549
A deletion of the start codon at position 549
A transversion at position two of the codon in position 549
A transition at position two of the codon in position 549