Fact 1: Telephones are used for communication by two people by transmitting sound.

Fact 2: Sound Sound waves are mechanical waves.

Given the two facts above, answer the question "Telephones are used for communication by two people by transmitting what? " with the following options: 
- Transmitting illness.
 - chemical messengers
 - encoded information
 - electromagnetic energy
 - Television.
 - Communication degree.
 - Mechanical waves.
 - Electrical energy


 

       Mechanical waves.  