It's infrequent, but our own nucleotide sequences can change as the result of spontaneous or environmental damage (which might remove or shift a nucleotide position). what does this change?
select one:
a. it changes the gene involved, and can then change the protein.
b. it changes organisms into fundamentally different organisms.
c. we are not certain what happens. it's never been documented.
d. it changes nothing because of the almost infinite combinations of sequences.

The answer is A.

Nucleotide sequences are our genetic messages that allow cells to build proteins (aka polypeptides). When the sequence changes, the genetic code can be altered, and therefore the outcome of protein translation can be changed.

B is wrong because the gene change may not even affect the protein, and even if it does, it may not even have a measurable effect on the organism. And it's unlikely that one gene change will change an animal into a different animal. 

C is wrong because there's literally entire fields of genetic biology/microbiology dedicated to this subject. 

D is wrong because wtf does it even mean? And yes, change in your genetic code can have impact. It's more or less how cancer happens.