If you notice that two waves combine and a part of the resulting wave has less light intensity than either of the individual waves, you're observing a. destructive interference. b. polarization. c. constructive interference. d. diffraction.

If you notice that two waves combine and a part of the resulting wave has less light intensity than either of the individual waves, you're observing destructive interference. Destructive interference happens when the two waves that combine have amplitudes with opposite signs,which results in subtraction- combined wave with a lower amplitude.