The correct answer is: C. Potential divider bias
Potential divider bias is the most stable biasing method because it uses two resistors to divide the supply voltage, which provides a more stable reference voltage for the base of the transistor. This results in a smaller change in collector current for a given change in base current, which makes the circuit less sensitive to changes in temperature and other factors.
Base resistor bias is a simple biasing method that uses a single resistor to bias the base of the transistor. However, it is not as stable as potential divider bias because the base current is directly proportional to the supply voltage. This means that a small change in supply voltage can cause a large change in base current, which can destabilize the circuit.
Collector feedback bias is a more complex biasing method that uses a resistor to connect the collector of the transistor to the base. This provides a negative feedback signal that helps to stabilize the operating point of the transistor. However, it is not as stable as potential divider bias because the feedback signal is dependent on the collector current. This means that a small change in collector current can cause a large change in the feedback signal, which can destabilize the circuit.
None of the above is not a valid option.