b$.$ Does $\underset{x4}{lim}f(x)$ exist? If so$,$ what is it$?$ If not, why not? Select the correct choice below and, if necessary, fill in any answer box in your choice.

A$.$ Yes, $\underset{x4}{lim}f(x)$ exists and equals $$

$($Simplify your answer.$)$

B$.$ No$,\underset{x4}{lim}f(x)$ does not exist because $f(4)$ is undefined.

C$.$ No$,\underset{x4}{lim}f(x)$ does not exist because $\underset{x{4}^{+}}{lim}f(x)\underset{x{4}^{-}}{lim}f(x).$