Answer:
D. y = f(x/-1)
Step-by-step explanation:
The function f(x) is reflected across the y-axis to make the red graph. Such a reflection is accomplished by a horizontal scale factor of -1.
For some horizontal scale factor k, the transformed function is ...
y = f(x/k)
Here, we have k = -1, so the transformed function is ...
y = f(x/-1)
