The solution of the equation $\left| \begin{array}{ccc} \cos \theta & \sin \theta & \cos \theta \\ -\sin \theta & \cos \theta & \sin \theta \\ -\cos \theta & -\sin \theta & \cos \theta \end{array} \right| = 0$ is:

• A
  $\theta = n\pi$
• B
  $\theta = 2n\pi \pm \frac{\pi}{2}$
• C
  $\theta = n\pi \pm (-1)^n \frac{\pi}{4}$
• D
  $\theta = 2n\pi \pm \frac{\pi}{4}$