If A=(1234)A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}A=(1324) and B=(5678)B = \begin{pmatrix} 5 & 6 \\ 7 & 8 \end{pmatrix}B=(5768), which of the following equals (AB)T(AB)^T(AB)T?
ATBTA^T B^TATBT
BTATB^T A^TBTAT
BABABA
ATBA^T BATB