If $f(x) = [x] - [\frac{x}{4}]$,$x \in R$,where $[x]$ denotes the greatest integer function,then:

• A
  $\lim_{x \rightarrow 4^{-}} f(x)$ exists,but $\lim_{x \rightarrow 4^{+}} f(x)$ does not exist.
• B
  $f(x)$ is continuous at $x = 4$.
• C
  $\lim_{x \rightarrow 4^{+}} f(x)$ exists,but $\lim_{x \rightarrow 4^{-}} f(x)$ does not exist.
• D
  Both $\lim_{x \rightarrow 4^{-}} f(x)$ and $\lim_{x \rightarrow 4^{+}} f(x)$ exist,but are not equal.