1. **State the problem:** We need to find the element in the 3rd row and 2nd column of the product matrix $AB$, denoted as $(AB)_{3,2}$.
2. **Recall matrix multiplication rule:** The element $(AB)_{i,j}$ is calculated as the dot product of the $i$th row of $A$ and the $j$th column of $B$:
$$ (AB)_{i,j} = \sum_{k=1}^n A_{i,k} B_{k,j} $$
where $n$ is the number of columns in $A$ (which must equal the number of rows in $B$).
3. **Check dimensions:**
Matrix $A$ is $3 \times 4$ and matrix $B$ is $4 \times 2$, so multiplication $AB$ is defined and the result is a $3 \times 2$ matrix.
4. **Extract the 3rd row of $A$ and 2nd column of $B$:**
$$ A_{3,:} = [-1, -2, -3, -4] $$
$$ B_{:,2} = \begin{bmatrix} 0 \\ 1 \\ 0 \\ -1 \end{bmatrix} $$
5. **Calculate $(AB)_{3,2}$:**
$$ (AB)_{3,2} = (-1) \times 0 + (-2) \times 1 + (-3) \times 0 + (-4) \times (-1) $$
$$ = 0 - 2 + 0 + 4 $$
$$ = 2 $$
6. **Final answer:** $(AB)_{3,2} = 2$.
Therefore, the correct choice is E. 2.
Matrix Multiplication 35B86A
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