General solution of the differential equation $$(D^2 - 2D + 1)y = e^x$$ is

A

$$Ae^x + Be^{-x} + \frac {x^2}{2}e^x$$

B

$$e^x (A + Bx) - \frac {x^2}{2}e^x$$

C

$$Ae^x + Be^{-x} - \frac {x^2}{2}e^x$$

D

$$e^x (A + Bx) + \frac {x^2}{2}e^x$$