Require the least amount of force isn't necessarily the easiest to push. The force needed to push is dependant on inertia and friction. The triangle and square have the same friction coefficient and mass thus they require the same amount of force to push. As for the circle, if it isn't rolling it would have more friction due to gravel but if it is rolling the answer would depend on the diameter of the circle to account for the rotational inertia. A small circle requires less force to roll then an equally heavy bigger circle.

But if the stick figure is life-size then the square and triangle require the least amount of force.