Answer:
The correct answer is sound waves.
Explanation:
Mechanical waves are the waves which require a medium to travel from one place to another.
Sound waves are mechanical waves and these waves travel faster in a dense medium to transfer the kinetic energy between different objects, and produce vibrations.
That is the reason for their speed in a denser medium. Denser the medium more will be the speed of sound waves. Thus a denser material produces faster sounds waves.
