Which pitot-static instrument utilizes the pitot tube?

The airspeed indicator is the only instrument among the listed options that utilizes the pitot tube. The pitot tube measures dynamic air pressure, which is crucial for determining the aircraft's airspeed.

When air flows into the pitot tube, it creates pressure, which is then compared to static pressure from the static port. This difference in pressure allows the airspeed indicator to calculate and display the aircraft's speed through the air.

In contrast, the vertical speed indicator (VSI) and altimeter rely solely on static pressure. The VSI measures changes in static pressure over time to report the rate of climb or descent, while the altimeter uses static pressure to determine altitude. The magneto, on the other hand, is part of the ignition system and does not relate to the pitot-static system at all. Thus, the airspeed indicator stands out as the correct answer, as it directly imparts information from the pitot tube.