$\text{A.}$ $\left[0, \frac{\pi}{4}\right]$
$\text{B.}$ $\left[\frac{3 \pi}{4}, \pi\right)$
$\text{C.}$ $\left[0, \frac{\pi}{4}\right] \cup\left(\frac{\pi}{2}, \pi\right)$
$\text{D.}$ $\left[\frac{\pi}{4}, \frac{\pi}{2}\right) \cup\left[\frac{3 \pi}{4}, \pi\right)$
$\text{E.}$
$\text{F.}$