Ans: C
Note that $z=\dfrac{kx}{y}$, where $k$ is a non-zero constant.
Note that $z=\dfrac{kx}{y}$, where $k$ is a non-zero constant.
When $x=3$ and $y=4$, $z=18$. Then, we have
$\begin{array}{rcl}
18 & = & \dfrac{3k}{4} \\
k & = & 24
\end{array}$
$\therefore z=\dfrac{24x}{y}$.
When $x=2$ and $z=8$, we have
$\begin{array}{rcl}
8 & = & \dfrac{24(2)}{y} \\
y & = & 6
\end{array}$
