The correct answer is option 'b', inductive circuit.

Inductive Circuit:
- An inductive circuit consists of inductors, which are passive electronic components that store energy in the form of a magnetic field.
- In an inductive circuit, the current lags behind the voltage waveform because of the inductance present.
- The inductive reactance (XL) in the circuit opposes the flow of current, which results in the current lagging behind the voltage.
- In an inductive circuit, the power factor is defined as the cosine of the phase angle between the voltage and current waveforms.

Power Factor:
- Power factor is a measure of how effectively electrical power is being used in a circuit.
- It is the ratio of the real power (the power that is actually used to do work) to the apparent power (the product of the voltage and current).
- The power factor ranges between 0 and 1, with 1 indicating a purely resistive circuit (ideal) and 0 indicating a purely reactive circuit (no real power being used).

Explanation:
- In an inductive circuit, the power factor is minimum.
- This is because the inductive reactance causes the current to lag behind the voltage, resulting in a phase shift between the two waveforms.
- The power factor is equal to the cosine of the phase angle between the voltage and current waveforms.
- Since the current lags behind the voltage in an inductive circuit, the power factor will be less than 1, and closer to 0.
- The closer the power factor is to 0, the more reactive power is present in the circuit, indicating that a significant portion of the supplied power is not being used effectively.

Effect of Low Power Factor:
- A low power factor can have several negative effects on an electrical system.
- It leads to higher energy consumption, as more apparent power needs to be supplied to compensate for the reactive power.
- It can result in increased voltage drops and power losses in the distribution system.
- It reduces the overall efficiency of the system and can lead to increased electricity costs.
- Low power factor can also cause equipment overheating and premature failure.

Conclusion:
- In an inductive circuit, the power factor is minimum due to the inductive reactance causing a phase shift between the voltage and current waveforms.
- It is important to improve the power factor in electrical systems to optimize energy usage, reduce losses, and ensure efficient operation of equipment.