Final answer:
The equation for the line of reflection is y = -x. The correct answer is option C) y = x.
Step-by-step explanation:
The equation for the line of reflection can be determined by finding the equation of the line and then negating the y-values. In this case, the equation of the line is y = x, so the equation for the line of reflection is y = -x.
Therefore, the correct answer is option C) y = x.