Equation of a common tangent to the circle, $x^2+y^2-6x=0$ and the parabola, $y^2=4x$, is :

(1) $2\sqrt3y=12x+1$

(2) $2\sqrt3y=-x-12$

(3) $\sqrt3y=x+3$

(4) $\sqrt3y=3x+1$

(1) $2\sqrt3y=12x+1$

(2) $2\sqrt3y=-x-12$

(3) $\sqrt3y=x+3$

(4) $\sqrt3y=3x+1$