The correct answer is option 1, which states that only statement 1 is correct.

Let`s discuss each statement to understand why this is the correct answer:

1. The statement "as the tsunamis leave the deep water of the open sea and travel towards shallow water, the speed is reduced considerably" is correct. Tsunamis travel at high speeds in deep water, but as they approach shallow water, their speed decreases due to the friction between the waves and the ocean floor. This reduction in speed is a significant characteristic of tsunamis.

2. The statement "they attain enormous height" is incorrect. Tsunamis are characterized by their long wavelengths, which can stretch for hundreds of kilometers. However, their height is usually not as significant, especially as they approach the coastline. While the height of a tsunami can increase when it reaches shallow water and encounters an underwater slope, it typically does not reach enormous heights.

3. The statement "they appear as a gentle rise and fall of the sea" is incorrect. Tsunamis are not a gentle rise and fall of the sea like regular waves or tides. They are a series of powerful and destructive waves caused by seismic activity, such as an earthquake or volcanic eruption. Tsun