If for $$p \neq q \neq 0$$, the function $$f(x) = \frac{7\sqrt[p]{729+x} - 3}{\sqrt[3]{729+qx} - 9}$$ is continuous at $$x = 0$$, then

A

$$7pqf(0) - 1 = 0$$

B

$$63qf(0) - p^2 = 0$$

C

$$21qf(0) - p^2 = 0$$

D

$$7pqf(0) - 9 = 0$$