The axis of a parabola is along the line `y=x` and the distance of its vertex and focus from the origin are `sqrt(2)` and `2sqrt(2)` , respectively. If vertex and focus both lie in the first quadrant, then the equation of the parabola is
(a) `(x+y)^2=(x-y-2)` (b)`(x-y)^2=(x+y-2)` (c)`(x-y)^2=4(x+y-2)` (d)`(x-y)^2=8(x+y-2)`