Answer:
The cytosine-adenine-adenine pair is not an example of mutation.
Step-by-step explanation:
In the base pairing of DNA, adenine bonds only with thymine and guanine bonds with cytosine. As guanines and adenines are purines and thymine and cytosine are pyrimidine in DNA, and due to their structure, there is only small space in between them to fit a purine and pyrimidine and not more than that.
Therefore, these constructions of two adenines are not possible with cytosine. Thus, this cannot be an example of mutation.