If moment generating function of continuous random variable X is $$\frac{\lambda}{\lambda - t} ; t< \lambda$$, then E($$X^{3}$$) equals to:

A

$$\frac{4}{\lambda^{3}}$$

B

$$\frac{8}{\lambda^{3}}$$

C

$$\frac{6}{\lambda^{3}}$$

D

$$\frac{2}{\lambda^{3}}$$