Which law explains how rockets are launched into space?
I would go with Newton's 3rd Law
Newton's 3rd Law states that for every action, there is an equal and opposite reaction. So, when rocket fuel is burned and pushed out the bottom of the rocket, the ground pushes back with an equal amount of force.
This continues as the rocket rises from the ground, although as it flies through the atmosphere, it is the air itself that the expelled gases push against.