I should think the law of gravity because the ice skater leaping into the air off the ground will inevitably be brought back to ground by gravity. The situation also has something to do with Newton's laws on motion acceleration, mass and motion but I think the law of gravity defeats all.
Force, when the skater pushes off the ground. Gravity, when the skater is pulled back down. And momentum, when the skater lands and is usually still moving around the same speed as they were before the jump.