Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: One key physical process in beach formation is wave action. Sand is deposited on beaches as waves break onto the shoreline and the energy from the wave scatters. Which type of energy is most used by wave action to modify the shape of the beaches?
mechanical
Kinetic energy.