Find the values of $k$ for which the line $(k-3)x-(4-k^2)y+k^2-7k+6=0$ is Parallel to the $y$ axis.

Question

$\begin {array} {1 1} (A)\;k=2 & \quad (B)\;k=-2 \\ (C)\;k=\pm 2 & \quad (D)\;\text{ none of the above } \end {array}$