Ans: A
For the straight lines are perpendicular to each other, the product of their slopes is $-1$. Then we have
For the straight lines are perpendicular to each other, the product of their slopes is $-1$. Then we have
$\begin{array}{rcl}
\dfrac{-3}{2} \times \dfrac{-k}{12} & = & -1 \\
3k & = & -24 \\
k & = & -8
\end{array}$
