Correct Option: C

The phenomena of interference and diffraction of light were successful beyond doubt to prove that light is a form of wave. But they failed to decide whether light is transverse or longitudinal wave. The fact that light is a transverse wave was established only after the discovery of the phenomenon of polarization. It was Huygens who first discovered the phenomenon of polarization in 1690. The phenomenon of interference and diffraction can be exhibited by all types of waves but polarization can be exhibited by the transverse waves only. So it was the discovery of polarization of light that helped us to prove that light is a transverse wave.