Find the value of $k$ for which the equation $2x^2-(k-1)x+8=0$ will have real and equal roots.

Question

$\begin{array}{1 1} (a)\;-7 \geq k \geq 9 \\ (b)\; -7 \leq k \leq 9 \\(c)\; -7 < k \leq 9 \\ (d)\; -7>k>9 \end{array}$