Find the value of the expression :$\cos^4\large\frac{\pi}{8}$$+\cos^4\large\frac{3\pi}{8}$$+\cos^4\large\frac{5\pi}{8}$$+\cos^4\large\frac{7\pi}{8}$

Question

$\begin{array}{1 1}(A)\;\large\frac{1}{2}&(B)\;\large\frac{3}{2}\\(C)\;\large\frac{\sqrt 2}{2}&(D)\;\large\frac{1}{4}\end{array} $