Here is a goal: How can I keep my chair cushions from sliding?

Which way makes more sense to accomplish this goal?

Choose from:
(I) Buy a piece of thin, non-slip rug padding that's used under area rugs. Cut it about 1 in. smaller than the chair cushion all the way around. Then just lay it in place under the cushion.;
(II) Buy a piece of thin, non-slip rug padding that's used under area rugs. Cut it about 1 in. smaller than the chair cushion all the way around. Then just lay it in place over the cushion.;
(I)