By definition, insertion is a type of mutation that involves the addition of one or more nucleotides into a segment of DNA. An example of this type of mutation is Crohn's disease. This condition has an association with the NOD2 gene. In fact, the mutation of this gene is an insertion of a Cytosine at position 3020. Specifically in Crohn's disease, there is a C-insertion polymorphism in the NOD2 gene (3020insC) on chromosome 16. Further, other gene mutations have also been described, such as mutations in the ATG16L1, IL23R, and IRGM.
We can conclude that the correct answer is:
Answer:A. Insertion
