A

\[R - \left\{ k\pi + \frac{\pi}{4}/k \in \mathbb{Z}\right\}\]

B

\[R - \left\{k\pi+\frac{2\pi}{2}/k \in \mathbb{Z} \right\}\]

C

\[R-\left\{(2x+1)\frac{\pi}{2}/k \in \mathbb{Z} \right\}\]

D

\[R-\left\{k\frac{\pi}{3} /K \in \mathbb{Z} \right\}\]

E

\[R-\left\{k \pi / k \in \mathbb{Z}\right\}\]