If $y=2x+c$ is a tangent to $y=2x^2-3x+4$, find c

Question

$\begin{array}{1 1} (a)\;\frac{-7}{8} \\ (b)\;\frac{-8}{7} \\ (c)\;\frac{7}{8} \\(d)\;\frac{8}{7} \end{array}$