What type of modulator specifically designed to change inductance or capacitance in the oscillator tank circuit?

The correct answer is based on the function of a mechanical modulator within the oscillator tank circuit. Mechanical modulators can adjust physical components such as inductors or capacitors, thereby altering the properties of the tank circuit. In oscillator systems, maintaining resonance is crucial, and directly modifying inductance or capacitance is a way to achieve this.

Mechanical modulators work by physically changing the arrangement of components or by applying forces that impact the values of inductance or capacitance. For instance, varying the tension in a spring or changing the position of a movable capacitor plate can directly influence the tank circuit's resonance frequency.

Other types of modulators, such as electrical, digital, or analog modulators, typically rely on electronic signals to influence oscillation or modulation, rather than directly altering physical attributes of the circuit components themselves. This distinct capability of mechanical modulators makes them particularly relevant in specific applications requiring precise physical adjustments in oscillation circuits.