If $$\sin x = \frac{1}{2}$$ and $$\sin y = \frac{2}{3}$$, then what is the value of $$\left[\frac{(6 \cos^2 x - 4 \cos^4 x)}{(18 \cos^2 y - 27 \cos^4 y)}\right]$$

A

$$\frac{27}{20}$$

B

$$\frac{15}{14}$$

C

$$\frac{25}{21}$$

D

$$\frac{17}{14}$$