Final answer:
Thymine mispaired with guanine after DNA replication is typically repaired by the Mismatch Repair Mechanism, which involves excising the incorrect base and replacing it with the correct one.
Step-by-step explanation:
After replication is completed and a thymine base is found to be incorrectly paired with a guanine, the issue will generally be fixed by the Mismatch Repair Mechanism (C). During DNA replication, DNA polymerase has a proofreading function that corrects most mistakes. However, if an error is not immediately corrected, the mismatch repair system comes into play. Specifically, this mechanism involves enzymes recognizing the mispaired nucleotide, excising the portion of the DNA strand containing the incorrect base, and then replacing it with the correct base. This system is essential in maintaining the integrity of the genetic information and preventing mutations from becoming permanent.