Let $\alpha, \beta$ be the roots of the equation $x^2 - px + r = 0$ and $\frac{\alpha}{2}, 2\beta$ be the roots of the equation $x^2 - qx + r = 0$. Then the value of $r$ is\\
(A) $\frac{2}{9}(p-q)(2q-p)$\\
(B) $\frac{2}{9}(q-p)(2p-q)$\\
(C) $\frac{2}{9}(q-2p)(2q-p)$\\
(D) $\frac{2}{9}(2p-q)(2q-p)$