Use a CAS to Plot the Function near the Point $f ( x )$

Use a CAS to plot the function near the point x0 being approached. From your plot guess the value of the limit.
-What conditions, when present, are sufficient to conclude that a function $f ( x )$ has a limit as $x$ approaches some value of a?

A) The limit of $f ( x )$ as $x \rightarrow a$ from the left exists, the limit of $f ( x )$ as $x \rightarrow$ from the right exists, and these two limits are the same.
B) The limit of $f ( x )$ as $x \rightarrow$ a from the left exists, the limit of $f ( x )$ as $x \rightarrow$ from the right exists, and at least one of these limits is the same as $f ( a )$ .
C) Either the limit of $f ( x )$ as $x \rightarrow a$ from the left exists or the limit of $f ( x )$ as $x \rightarrow a$ from the right exists
D) $f ( a )$ exists, the limit of $f ( x )$ as $x \rightarrow$ from the left exists, and the limit of $f ( x )$ as $x \rightarrow$ from the right exists.