Imagine that one side of a dna molecule has the following chemical base sequence: c-g-a-a-t which of the following represents a genetic mutation of the sequence? c-g-a-a-t or c-g-a-t-t

The correct option is C-G-A-T-T

Genetic mutation is permanent change in either of the two:

a) Single building block ( a unit base pair, A, G, C, T)

OR

b) Change in the Codon (triple base pair like AGG TCT etc.) or a large part of the chromosome.

In this question there is a change in single building block and thus, it is a genetic mutation.