MCQ
Function $f(x) = \left\{ {\begin{array}{*{20}{c}} {sgn \left( {\left[ x \right]} \right)\,\,\,\,;\,\,\,x \ne I} \\ {\left[ {sgn \left( x \right)} \right]\,\,\,;\,\,\,x = I} \end{array}} \right.$ is '( where $sgn ()$ denotes signum function $and$ $[.]$ denotes greatest integer function )
- AContinuous but not differentiable at $x = 2$
- BDiscontinuous at every integer
- ✓Non differentiable at $x = 0\,\,and\,\,1$ only
- DNon differentiable at every natural number
