Answer
$y=\tan{x}$
Work Step by Step
The graph is increasing in its entire domain.
This means that the graph could either be that of the tangent or the cotangent function.
Recall that the tangent function is undefined in when $x$ is an odd multiple of $\frac{\pi}{2}$, while the cotangent function is undefined when $x$ is a multiple of $\pi$.
The given graph has the vertical asymptotes $x=-\frac{\pi}{2}$ and $\frac{\pi}{2}$, which means that the function it represents is undefined for these values.
Therefore, the function whose graph is given must be the basic tangent function.
