Answer the following question given this paragraph: 

The wavelength of a transverse wave can be measured as the distance between two adjacent crests. The wavelength of a longitudinal wave can be measured as the distance between two adjacent compressions.


Q: The wavelength of a what type of wave can be measured as the distance between two adjacent compressions?

 Choices:

- horizontal

- lateral

- vertical

- longitudinal

A:
longitudinal
