The sum of the distinct real values of $$\mu$$ for which the vectors $$\mu\hat{i} + \hat{j} + \hat{k}$$, $$\hat{i} + \mu\hat{j} + \hat{k}$$, $$\hat{i} + \hat{j} + \mu\hat{k}$$ are co-planar, is

A

0

B

$$-1$$

C

1

D

2