Answer is a reflection
Step-by-step explanation
Reflection over the y axis rule is
(x, y) ➡️ ( -x, y)
We can use any point on the pre image to check our work. Let’s use point C at ( -3, 1) moving to image C’ at point (3, 1)
The rule is correct
(x, y) ➡️ ( -x, y)
( -3, 1) ➡️ ( 3, 1)
See attachment