#### Answer

$y$

#### Work Step by Step

RECALL:
The graph of the function $y=f(-x)$ involves a reflection about the y-axis of the parent function $f(x)$.
The parent function of the given function is $y=\sqrt{x}$.
The given function is in the form $y=f(-x)$.
Therefore, the given function involves a reflection about the y-axis of the parent function $y=\sqrt{x}$.