Simplify the given expression.
$$\left(x - \frac{2}{x}\right)^3 - \left(x + \frac{2}{x}\right)^3$$

A

$$-4 \left(3x + \frac{4}{x^3}\right)$$

B

$$4 \left(3x - \frac{4}{x^3}\right)$$

C

$$-4 \left(x + \frac{4}{x^3}\right)$$

D

$$2 \left(x - \frac{4}{x^3}\right)$$