Explain how standing waves are produced? (select all that apply.) hint the waves must have the same speed, though the frequencies and wavelengths of each may be different. the waves must have the same frequency, amplitude and wavelength. the waves must have the same frequency and wavelength, but can have different amplitudes. the wave is confined within boundaries. waves traveling in opposite directions continuously interfere with each other. waves traveling in the same direction continuously interfere with each other. standing waves only occur in sound waves. standing waves only occur in waves traveling along strings. the waves must have the same amplitude, but can have different frequencies and wavelengths.