A \( \left[0, \frac{\pi}{2}\right) \cup\left[\pi, \frac{3 \pi}{2}\right) \)
B \( \left[0, \frac{\pi}{6}\right] \cup\left(\frac{\pi}{3}, \frac{\pi}{2}\right] \)
C \( \left[0, \frac{\pi}{2}\right] \cup\left(\pi, \frac{3 \pi}{2}\right] \)
D \( \left(-\frac{\pi}{2}, \frac{\pi}{4}\right] \cup\left[\frac{\pi}{2}, \pi\right) \)