A point P(x,y)P(x, y)P(x,y) is transformed by T(x,y)=(−x,−y)T(x, y) = (-x, -y)T(x,y)=(−x,−y). What is the effect?
Reflection across the x-axis
Reflection across the y-axis
Reflection across the origin
Rotation of 90∘90^\circ90∘