The fourth proportional to $$a^{3} + a^{2}b + ab^{2} , a + b$$ and $$a^{2} + ab + b^{2}$$ is:

A

$$\frac{b}{a + b}$$

B

$$1 + \frac{b}{b}$$

C

$$\frac{a}{a + b}$$

D

$$1 + \frac{b}{a}$$