Below Are Short Fragments of DNA Sequences from Two Yeast

Below are short fragments of DNA sequences from two yeast strains (A and B) , which have been diverging from each other, as well as a short fragment from their common ancestor (C) .

Yeast A: TGACTGCAAACATCCTAG
Yeast B: TGCCTGGACACATCGAAG
Yeast C: TGCCTGGAAACCTCCTAG

What is the minimum number of evolutionary changes that have occurred since strains A and B evolved from their common ancestor?

A) three
B) four
C) five
D) six
E) seven