The correct answer is: A. A pure resistive load.
A class C amplifier is a type of transistor amplifier that operates in the saturation region. This means that the transistor is always turned on, and the output signal is a square wave. A square wave is a pure resistive load, because it has no reactive components (inductance or capacitance).
A pure inductive load is a load that has no resistance and only inductance. A pure capacitive load is a load that has no resistance and only capacitance. A resonant tank is a circuit that consists of an inductor and a capacitor connected in parallel. A resonant tank has a high impedance at its resonant frequency.
In conclusion, a class C amplifier always drives a pure resistive load.