Find the Indicated Sum or Difference, If It Is Defined

Multiple Choice

Find the indicated sum or difference, if it is defined.
- $$\left[ \begin{array} { r r } - 1 & 5 \\0 & 4 \\8 & - 4\end{array} \right] - \left[ \begin{array} { l l } 2 & 1 \\7 & 4 \\4 & 2\end{array} \right]$$

A) $\left[ \begin{array} { r r } - 3 & 4 \\ - 7 & 0 \\ 4 & - 6 \end{array} \right]$
B) $\left[ \begin{array} { r r } 3 & - 4 \\ 7 & 0 \\ - 4 & 6 \end{array} \right]$
C) not defined
D) $\left[ \begin{array} { r r } 1 & 6 \\ 7 & 8 \\ 12 & - 2 \end{array} \right]$