A variable circle passes through the fixed point $$A(p, q)$$ and touches $$x$$-axis. The locus of the other end of the diameter through $$A$$ is

A

$$(x - p)^2 = 4qy$$

B

$$(x - q)^2 = 4py$$

C

$$(y - p)^2 = 4qx$$

D

$$(y - q)^2 = 4px$$