What instrument displays the aircraft's airspeed, typically in knots, to the pilot?

The instrument that displays the aircraft's airspeed, typically in knots, is the airspeed indicator. This instrument is essential for pilots as it measures the dynamic pressure of air flowing over the aircraft, allowing them to determine how fast they are moving through the air. The airspeed indicator provides crucial information for various phases of flight, including takeoff, cruising, and landing, helping pilots maintain safe and efficient flying conditions.

In contrast, the vertical speed indicator measures the rate of ascent or descent, the ground speed indicator provides the aircraft's speed relative to the ground rather than through the air, and the Mach meter indicates the aircraft's speed in relation to the speed of sound. Each of these instruments serves a specific purpose, but they do not provide the airspeed readings that are vital for operational control during flight, making the airspeed indicator the correct choice.