The system of equations $$\alpha x + y + z = \alpha - 1$$, $$x + \alpha y + z = \alpha - 1$$, $$x + y + \alpha z = \alpha - 1$$ has no solution, if $$\alpha$$ is

A

$$-2$$

B

either $$-2$$ or $$1$$

C

not $$-2$$

D

$$1$$