Determine the values of $x\in (-3,3)$ at which $f$ is not differentiable using the following graph:

• A. $x=-2$, $x=0$, $x=1$
• B. $x=-1$, $x=0$
• C. $x=0$, $x=2$
• D. $x=-1$, $x=0$, $x=1$