Answer:
The correct answer is "C-to-T transition".
Step-by-step explanation:
When cytosine is hydrolysed or methylated it could result in the formation of an uracil via the deamination of cytosine. The uracil that is formed in the genomic DNA could be repaired by DNA repair pathways, but it could result in the formation of a tyrosine. These series of mutations are known as "C-to-T transition" because it starts with a cytosine and ends with a tyrosine. This kind of somatic mutations are very studied because they had been found in human breast tumors.