The value of $\cos^248^{\large\circ}-\sin^212^{\large\circ}$ is

Question

$\begin{array}{1 1}(A)\;\large\frac{\sqrt 5+1}{8}&(B)\;\large\frac{-\sqrt 5-1}{8}\\(C)\;\large\frac{\sqrt 5+1}{5}&(D)\;\large\frac{\sqrt 5+1}{2\sqrt 2}\end{array} $