The equation of the plane which makes double the intercepts of the plane $3x+6y-z+12=0$ is ?

Question

$(a)\:6x+12y-2z=1\:\:\qquad\:(b)\:3x+6y-z+6=0\:\:\qquad\:(c)\:3x+6y-z=1\:\:\qquad\:(d)\:3x+6y-z+24=0$