Fact 1: Dropping an object into water causes vibrations in the water.

Fact 2: By it's nature, a vibration is a frequency wave .

Given the two facts above, answer the question "what does dropping an object into water cause?" with the following options: 
- oxygen
 - chemical changes
 - kinetic energy
 - radiation
 - freezing
 - activation energy
 - frequency waves
 - heat energy


 

       frequency waves  