If $$\cot \theta = \sqrt7$$, then the value of $$\frac{\cosec^2 \theta - \sec^2 \theta}{\cosec^2 \theta + \sec^2 \theta}$$ is:

A

$$\frac{7}{9}$$

B

$$\frac{3}{4}$$

C

$$\frac{8}{9}$$

D

$$\frac{2}{3}$$