A high-speed camera is used to capture the profile of a surface water wave propagating in a narrow wave tank. The resulting displacement-distance graph is shown below.
What is the wavelength of this wave?
2.5 mm2.5\text{ mm}2.5 mm
8.0 mm8.0\text{ mm}8.0 mm
16 mm16\text{ mm}16 mm
40 mm40\text{ mm}40 mm