The equation of the plane which is parallel to the plane $x-2y+2z-5=0$ and which is at a unit distance from origin is ?

Question

$\begin{array}{1 1} (a)\;x-2y+2z-3=0\:\:\:\qquad\:\:(b)\:\:x-2y+2z+1=0\:\:\qquad\:\:(c)\:\:x-2y+2z-1=0\:\:\qquad\:\:(d)\:\:x-2y+2z+5=0 \end{array}$