Let a, b, x and y be real numbers such that a - b = 1 and $$y \neq 0$$. If the complex number z = x + iy satisfies $$IM\left(\frac{az + b}{z+1}\right) = y$$, then which of the following is(are) possible value(s) of x?

A

$$-1 + \sqrt{1 - y^2}$$

B

$$-1 - \sqrt{1 - y^2}$$

C

$$1 + \sqrt{1 + y^2}$$

D

$$1 - \sqrt{1 - y^2}$$