A

$$y = A \cos 2x + B \sin 2x - \frac{1}{8} - \frac{x}{8} \sin 2x$$

B

$$y = A \cos 2x + B \sin 2x + \frac{1}{8} + \frac{x}{8} \sin 2x$$

C

$$y = A \cos 2x + B \sin 2x - \frac{1}{8} + \frac{x}{8} \sin 2x$$

D

$$y = A \cos 2x + B \sin 2x + \frac{1}{8} - \frac{x}{8} \sin 2x$$