B) (-5,3)
1) We need to locate the vertex location since the point here is to find the coordinates of C'. So, let's do it before applying the required transformation.
C(5,3)
2) Since we want to know the coordinates of C', and there was a reflection across the y-axis, we can write the following:
C(5,3) Rule (x,y) --> (-x,y) C'(-5,3)
3) Thus, the answer is (-5,3)
