Think 5 and 6

My answer : Heating the ring will allow the ball to pass through.They diameter of the inner ring will expand along with the thickness and the outer ring.The reason it expands and not contract is because when heated the molecules space out more but if the inner ring contract,instead it will bring the molecules closer.

My answer : When heated the molecules have more energy to escape the kinetic forces of attraction but when cooled down the thermal energy is transfer away and thus as it does not have that much energy,the kinetic forces of attraction will return the metal strip to its original shape.