If $$\alpha, \beta$$ are the roots of the equation $$7x^2 - 8x + 6 = 0$$ then $$(\alpha^2 + \beta^2)(\alpha + \beta) =$$

A

$$\frac{-20}{49}$$

B

$$\frac{20}{49}$$

C

$$\frac{-160}{343}$$

D

$$\frac{160}{343}$$