$$3[a - \frac{1}{a}] + [a - \frac{1}{a}]^{3} =$$?

A

$$a^{2} - \frac{1}{a^{3}}$$

B

$$a^{3} - \frac{1}{a^{3}}$$

C

$$a^{3} + \frac{1}{a^{3}}$$

D

$$a^{2} - \frac{1}{a^{2}}$$