What is an insertion mutation?

An insertion mutation occurs when one or more nucleotide base pairs are added into a DNA sequence. This addition can disrupt the normal sequence of the genetic code, potentially altering the function of the resulting protein. Insertion mutations can lead to significant changes in an organism’s traits, depending on where in the genome they occur and how they affect the sequence of codons (three-nucleotide sequences that code for amino acids).

While other types of mutations involve a variety of changes to the DNA, such as substitutions (swapping one base for another), deletions (loss of DNA), and frameshift mutations (which can be caused by insertions or deletions that change the reading frame), an insertion mutation is specifically defined by the increase in base pairs. This characteristic makes option C the correct answer.