#### Answer

$C$

#### Work Step by Step

RECALL:
(1) The graph of the equation of the form $x=a$ is a vertical line.
(2) The graph of the equation of the form $y=k$ is a horizontal line.
The given equation is in the form $y=k$ where $k=-5$.
Thus, its graph is a horizontal line.
Since $k$ is negative, then the horizontal line is below the x-axis.
Therefore, the answer is Option C.