ગણ $\{x \in R: \cos 2x + 2 \cos^2 x = 2\}$ એ શેના બરાબર છે?

• A
  $\{2n\pi + \frac{\pi}{3}: n \in Z\}$
• B
  $\{n\pi \pm \frac{\pi}{6}: n \in Z\}$
• C
  $\{n\pi + \frac{\pi}{3}: n \in Z\}$
• D
  $\{2n\pi - \frac{\pi}{3}: n \in Z\}$