Vertical asymptote:
A vertical asymptote is a value of x for which the function is not defined, that is, it is a point which is outside the domain of a function;
In a graphic, these vertical asymptotes are given by dashed vertical lines.
An example is a value of x for which the denominator of the function is 0.
In this graphic:
Dashed vertical lines at: , thus, for
and
the denominator is zero.
Thus, the function graphed is:
And the correct answer is given by option C.
To take a look at a problem with asymptote, you can check this item brainly.com/question/4084552.