If $$\sec^2 \theta + \tan^2 \theta = \frac{25}{18}$$, then the value of $$\sec^4 \theta - \tan^4 \theta$$ is:

A

$$\frac{18}{25}$$

B

$$\frac{25}{12}$$

C

$$\frac{25}{9}$$

D

$$\frac{25}{18}$$