Let $f(x)= \begin{cases}x^2+4 x, & -3 \leq x \leq 0 \\ -\sin x, & 0<x \leq \pi / 2 . \\ -\cos x-1, & \pi / 2<x \leq \pi\end{cases}$ Then, which one of the following is not true?

$x=-2$ is the point of global minimum $x=\pi$ is the point of global maximum $f(x)$ is not differentiable at $x=\frac{\pi}{2}$ $f(x)$ is discontinuous at $x=0$

$f(x)$ is discontinuous at $x=0$

It is evident from the graph of the function that options (a), (b) and (c) are true.