Answer:
Option (1)
Step-by-step explanation:
Sound waves are produced due to the vibration of any particular object. These waves propagate freely in air. When these sound waves change its medium from air to water, which is a denser medium, then the velocity of these waves gradually decreases. It is because, in the denser medium, the materials are compressed tightly and the speed of the sound waves in water decreases with the increasing water depth.
Thus, when the sound wave travels from air to water, it gradually slows down.
Hence, the correct answer is option (1).