In the point (a, – a) we have x coordinate as a , y coordinate as ( – a)

Hence we get

Taking y to the left hand side, we get

x + y = 0

A. Point on line x = a is of the form (a, y)

B. Point on line y = a is of the form (x, a)

C. Point on line x = y is of the form (a, a)

D. Point on line x + y = 0 is of the form (a, – a)

Hence D is the correct option.