When a person jumps horizontally off of the end of an unanchored boat in a lake the person goes forward and the boat goes backward. This is an example of?

This scenario demonstrates the principle of conservation of momentum. When the person jumps forward, they exert a force on the boat in the opposite direction, causing it to move backward. This interaction illustrates Newton's third law of motion, which states that for every action, there is an equal and opposite reaction.