What's an easy way to create an interference pattern of waves?

AShine a light onto a black surface; the dark color will interfere with the transmission of lightincorrect answer
BBroadcast radio waves from a tower; water particles in the atmosphere will interfere with the transmissionincorrect answer
CPlay music through a board with one hole in it; the board will interfere with the sound wavesincorrect answer
DToss two pebbles into the water close to each other; the waves from each pebble will interfere with the other

Correct answer: D

Tossing two pebbles into water close to each other will create ripples that interfere with each other, creating an interference pattern.