Properties of light that define light as a wave?
are the properties:
wavelength
amplitude
period
frequency
speed

or

reflection
refraction
dispersion
diffraction
interference

The first choices are correct, because the second choices could happen by things other than light.

I believe the correct answer from the two choices above is the first set of choice. Properties of light that define light as a wave are Wavelength, 
Amplitude, Period, Frequency and speed. These terms are used and calculated to define a light as a wave. Hope this answers the question.