Answer: D. The range stays the same, but the domain changes.
Explanation: A function can be reflected over or across an axis. When the function is reflected in the y-axis, it means:
g(x) = f(-x)
i.e, the x-values are opposite to the original function.
In the image below, when we reflected the function across the y-axis, the new one will be drawn at the positive x-axis but still at the negative y-axis as shown in red at the second attachment.
Domain of a function is all the values x can assume. Range of a function is all the results the variable y assume.
According to the new graph, y-values didn't change, so Range stays the same. However, x-values changed their signal. Therefore, domain changes.