If $5(\tan^2 x – \cos^2 x) = 2 \cos2x + 9$, then the value of $\cos 4 x$ is :

Question

( A ) $\frac{2}{9}$
( B ) $\frac{1}{3}$
( C ) $-\frac{7}{9}$
( D ) $-\frac{3}{5}$