Nico vibrates an object at different frequencies. At a certain frequency, the sound gets louder and then returns to the same volume when he moves to the next frequency.

The sound becomes louder at a particular driving frequency because the object resonates: energy transfers efficiently when the vibration matches a natural frequency. This can produce a standing wave with a larger vibration amplitude, making the sound louder. The correct choice is “A standing wave is being generated.”

AI-written and checked against the verified answer.