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Suppose $A$ is a $2\times3$ matrix, $B$ is a $3\times4$ matrix, and $C$ is a $4\times2$ matrix.

Which of the following choices lists two well defined matrices of the same size?

$AB$ and $BC$

$AB$ and $AC$

$AC$ and $(CA)^T$

$AC$ and $(AC)^{-1}$

$B$ and $A^TC^T$