Translocation and internalization of AQP5 have been shown to be regulated by the phosphorylation state of the S156 residue. Researchers later isolate another residue that tends to be phosphorylated at position 259 of the AQP5 protein. If they desire to replicate the results described in the passage (S156E) with a phosphomimetic mutant construct, this construct is most likely to be:

A. T259D.
B. Y259A.
C. F259E.
D. G259W.