$\text{ Let }[.]\text{ denote the greatest integer function and }f\left(x\right)=\left[{\tan }^{2}x\right]\text{. Then, }$

• A

  $\underset{x\to 0}{lim} f\left(x\right)\text{ does not exist }$

• B

  $f\left(x\right)\text{ is continuous at }x=0$

• C

  $f\left(x\right)\text{ is not differentiable at }x=0$

• D

  $f\left(0\right)=1$