The correct option is 0.5 M
Calculation
Wavelength is defined as the ratio of velocity of a wave to its frequency. It is measure in meters. Mathematically, wavelength is given by the following formula:
Wavelength = wave velocity / frequency
From the details given in the question,
Wavelength =?
Velocity = 340 m/s
Frequency = 680 HZ
Wavelength = 340 /680 = 0.5
Therefore, wavelength = 0.5 M