Which one of the statements about ultrasound waves and light waves is correct?
An ocean hydrophone records the pressure vibrations caused by a low-frequency acoustic wave travelling through water. The figure below shows the vibration recorded over a period of time.

Calculate the frequency of the wave shown in the trace.
Write down the equation which links wave speed, frequency, and wavelength.
The wave is travelling through seawater at a speed of 1500 m/s1500\text{ m/s}1500 m/s.
Calculate the wavelength of this wave.