Answer:
Substitution Mutation
Step-by-step explanation:
It can’t be deletion or addition as the base pairs of DNA haven’t shifted to the right or left.
If they had the second sequence would have an extra/one less base pair which isn’t the case.
It can’t be an inversion, as that’s where the base pairs from the opposite DNA strands are inverted/switched.
If it was inversion, you would have had a C instead of an A for Sample 2.
This is due to complementary base pairing where guanine bind with cytosine and adenine binds with thymine.
Therefore, this only leaves substitution as a viable answer.