Depurination results in the removal of a purine from a DNA strand, resulting in an apurinic site. In a region of the DNA, depurination occurs in a region where there is a GC base pair. What is the base in the deoxynucleotide that is added opposite the apurinic site in the first round of replication, if depurination in this region results in a change from a GC base pair to TA base pair