Which property of matter allows convection currents to form? fluids rise if they are less dense than the matter around them. the molecules in solids do not vibrate very quickly. electromagnetic waves carry energy. liquids take the shape of their container.

The answer is a : fluids rise if they are less dense than the matter around them ! i hope this helped, despite being so late

In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce sustained tones, beats can be readily recognized. So I believe D.