If $(x+iy)^{\large\frac{1}{3}}=a+ib$ then $\large\frac{x}{a}+\frac{y}{b}$ equals

Question

$\begin{array}{1 1}(A)\;2(a^2+b^2)&(B)\;2(a^2-b^2)\\(C)\;4(a^2+b^2)&(D)\;4(a^2-b^2)\end{array}$