Answer:
Diamond.
Step-by-step explanation:
Wavelength may be defined as the distance between two consecutive crest or trough of a wave. The S.I. unit of wavelength is meter.
Refractive index is inversely proportional to wavelength. The media with high refractive index has the shortest wavelength. Refractive index of ice is 1.31, refractive index of glass is 1.5, refractive index of water is 1.33 and refractive index of diamond is 2.4.Since, diamond has highest refractive index so it has shortest wavelength.
Thus, the correct answer is option (4).