The correct answer is option 4: Undersea Waves. A tsunami is a series of large ocean waves that can cause significant destruction when they reach the shore. Tsunamis are usually caused by underwater earthquakes, volcanic eruptions, or landslides, but they can also be triggered by meteorite impacts or man-made disturbances such as nuclear explosions. Unlike regular ocean waves, which are caused by wind, tsunamis are generated by a displacement of the ocean floor. This displacement creates a massive amount of energy that is transferred to the water above, causing the formation of extremely long, high-speed waves that travel across the ocean. When these waves reach shallow waters near the coast, they slow down and increase in height, resulting in the destructive force associated with tsunamis.