Simplify: $$(a^{-1}+b^{-1})\div(a^{-3}+b^{-3})$$

A

$$\frac{ab}{(a^{2}-ab+b^{2})}$$

B

$$\frac{a^{3}b^{3}}{(a^{2}-ab+b^{2})}$$

C

$$\frac{a^{2}b^{2}}{(a^{2}+ab+b^{2})}$$

D

$$\frac{a^{2}b^{2}}{(a^{2}-ab+b^{2})}$$