If $$x^{\frac{2}{3}} + y^{\frac{2}{3}} = a^{\frac{2}{3}}$$, then $$\frac{dy}{dx} =$$

A

$$a\left(\frac{y}{x}\right)$$

B

$$\left(\frac{y}{x}\right)^{\frac{1}{3}}$$

C

$$- \left(\frac{y}{x}\right)^{\frac{1}{3}}$$

D

$$a^{\frac{1}{3}}(y + x)^{\frac{1}{3}}$$