What does a gyro's operation primarily depend on?

A gyro's operation primarily depends on its resistance to deflection of the spinning wheel or disc. This resistance is a fundamental characteristic of gyroscopes stemming from the principles of angular momentum. When a wheel or disc spins, it exhibits stability and maintains its orientation due to gyroscopic inertia. As external forces are applied to change the direction or tilt of the gyro, the spinning action resists these changes, leading to a condition where the gyro tries to preserve its current orientation. This phenomenon allows gyros to be used effectively in navigation and stabilization systems, such as in aircraft attitude indicators and autopilots.

The other options highlight related concepts, but they don't capture the primary dependence of gyro operation as accurately. For instance, while the ability to resist precession is important, it comes into play as a secondary effect of the gyro's fundamental resistance to deflection. Additionally, angular velocity and the speed of the spinning wheel are factors that influence performance, but they do not define the core operational principle of gyros.