If the line $y=mx+c$ touches the hyperbola $\large\frac{x^2}{a^2}+\frac{y^2}{b^2}$$=1$ then find the value of c .

Question

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