Triangle PQR has vertices P(3, 5), Q(2, -1), and R(-6, 2). Triangle P'Q'R' has vertices P'(3, -5), Q'(2, 1), and R'(-6, -2). Which transformation of triangle PQR produced triangle P'Q'R'?
1) A rotation of 90° clockwise around the origin
2) A reflection across the y-axis
3) A rotation of 90° counterclockwise around the origin
4) A reflection across the x-axis
