Which of the following pairs (x,y)(x, y)(x,y) is a solution to the equation x2−2y2=7x^2 - 2y^2 = 7x2−2y2=7?
(3,1)(3, 1)(3,1)
(4,2)(4, 2)(4,2)
(5,3)(5, 3)(5,3)
(2,1)(2, 1)(2,1)