Here is the correct option: According to Newton's third law of motion, the balloon is pushed forward as the air is forced out. Newton's third law of motion states that for every action there is an equal and opposite reaction. This means that in every interaction, there is a pair of force that is acting on the interacting objects, the size of the force on the first object is equal to the size of the force on the second object.
So, the answer would be 20 cm
Fossil fuels is the answer