As a result of a mutation, the DNA sequence AGT - TGA-CAT changes to AAT - TGA - CAT. Which best describes the mutation?
It is a substitution in which the DNA base, G, was replaced with a different DNA base, A.
It is a deletion in which the DNA base, G, was replaced with a different DNA base, A.
It is a substitution in which three DNA bases, AGT, were replaced with three different DNA bases, AAT
It is a deletion in which three DNA bases, AGT, were replaced with three different DNA bases, AAT.