If the roots of the equation $(a^2+b^2)x^2-2(ac+bd)x+(c^2+d^2)=0$ are equal,then $\large\frac{a}{b}$=______

Question

$\begin{array}{1 1}(A) \; cd\\(B)\;\large\frac{d}{c} \\(C)\;\large\frac{c}{d} \\(D)\;\text{None of the above} \end{array}$