Mutations within a dna sequence
a)natural processes that produce genetic diversity
b)natural processes that always affect the phenotype
c)unnatural processes that always affect the phenotype
d) unnatural processes that are harmful to genetic diversity

The answer is A)natural processes that produce genetic diversity.

Mutations happen all the time but sometime they are not noticeable. Sometimes a  nucleotide can be substituted by another nucleotide and still originate the same aminoacid, which then gives us the same protein originaly programmed.
Other times, mutations can be noticeable, and in a bad way or in a good/neutral way that will give genetic diversity.

Genetic engineering is the answer.