If $$4 \sin^2 (2x - 10)^\circ = 3, 0 \leq (2x - 10) \leq 90$$, then find the value of $$\frac{\sin^4(x - 5)^\circ + \cos^4 (x - 5)^\circ}{1 - 2 \sin^2 (3x - 15)^\circ \cos^2(3x - 15)^\circ}$$

A

$$\frac{5}{8}$$

B

$$-1$$

C

$$1$$

D

$$-\frac{5}{8}$$