Find the equation of normal in slope form for the hyperbola?

Question

$\begin{array}{1 1}(a)\;y=mx\pm\large\frac{m(a^2+b^2)}{\sqrt{a^2+m^2b^2}}\\(b)\;y=mx\mp\large\frac{m(a^2+b^2)}{\sqrt{a^2-m^2b^2}}\\(c)\;y=mx\pm\large\frac{m(a^2-b^2)}{\sqrt{a^2+m^2b^2}}\\(d)\;\text{None of these}\end{array}$