Which of the following instruments produces sound by direct air flow across an opening?

The piccolo produces sound through direct air flow across an opening, which is a characteristic of many woodwind instruments. In the case of the piccolo, the player blows air across a small opening called a mouthpiece or embouchure hole, creating vibrations that produce sound. This mechanism is foundational in many woodwinds, where airflow across an opening yields a clear and bright tone.

In contrast, the saxophone, while also a woodwind instrument, produces sound using a single reed system where the reed vibrates against a mouthpiece when air is blown into it. The trumpet generates sound through the buzzing of the player's lips in the mouthpiece, using a different technique called lip vibration instead of a direct air flow across an opening. Likewise, the cello is a string instrument that produces sound through the vibration of strings, which are activated by bowing or plucking, rather than by air flow across an opening.