Point (3,1)(3, 1)(3,1) is reflected across the line y=xy=xy=x. What are the new coordinates?
(3,−1)(3, -1)(3,−1)
(−3,1)(-3, 1)(−3,1)
(−1,−3)(-1, -3)(−1,−3)
(1,3)(1, 3)(1,3)