If $$\frac{\sin\theta + \cos\theta}{\sin\theta - \cos\theta} = 3,$$ then the value of $$\sin^4 \theta - \cos^4 \theta$$ is

A

$$\frac {3}{5}$$

B

$$\frac {5}{3}$$

C

$$\frac {2}{5}$$

D

$$\frac {5}{2}$$