The value of $$\cos 255° + \sin 195°$$ is

A

$$\frac{\sqrt{3}-1}{2\sqrt{2}}$$

B

$$\frac{\sqrt{3}-1}{\sqrt{2}}$$

C

$$-\frac{\sqrt{3}-1}{\sqrt{2}}$$

D

$$\frac{\sqrt{3}+1}{\sqrt{2}}$$