The correct statement is: (b) Charges move through the circuit because the battery maintains an electric potential difference across the ends of the external circuit. This potential difference (voltage) sets up an electric field in the circuit, which drives the motion of charges through the resistor.​

Introduction

In a closed electric circuit with a battery and a resistor, charges move continuously because the battery creates and maintains an electric potential difference across the external circuit. This potential difference produces an electric field that drives charges through the resistor, where their electrical energy is converted into heat or other useful forms.​

Option (a) – “Resistor supplies energy”

Statement:
a. Charges move through the circuit because the resistor supplies energy.

• A resistor does not supply energy; it dissipates energy as heat, light, or other forms by opposing the motion of charges.​

• The resistor is the component where electrical potential energy of the charges decreases, so it cannot be the source driving the motion of charges.​

Therefore, option (a) is incorrect because the resistor consumes energy instead of supplying it.

Option (b) – “Battery maintains potential difference” (Correct)

Statement:
b. Charges move through the circuit because the battery maintains an electric potential difference across the ends of the external circuit.

• A battery is a source of electromotive force (emf); it maintains a fixed potential difference between its terminals by using chemical energy.​

• This potential difference creates an electric field in the closed conducting path, and that field exerts force on charges, causing them to move and form an electric current through the resistor.​

Hence, option (b) is correct, and it gives the proper physical reason for continuous charge motion in a closed circuit.

Option (c) – “Charges are supplied by the battery”

Statement:
c. Charges move because they are supplied by the battery.

• In metallic conductors, the mobile charges (electrons) are already present in the wire and resistor material before the battery is connected.​

• The battery’s main role is not to “supply” new charges, but to push existing charges by raising their potential energy as they pass through it, maintaining current in a closed loop.​

Thus, option (c) is misleading and effectively incorrect; the battery supplies energy and potential difference, not the charges themselves.

Option (d) – “Charges move to gain kinetic energy from resistor”

Statement:
d. Charges move through the circuit because they can acquire kinetic energy from the resistor.

• Charges lose electrical potential energy in the resistor, which is mostly converted into thermal energy due to collisions with the lattice ions; their average drift speed remains very small.​

• The resistor does not act as a source that gives kinetic energy to charges; instead, it is where energy is dissipated, so it cannot be the fundamental reason for their motion.​

Therefore, option (d) is incorrect because it reverses the actual energy flow: energy is lost in the resistor, not gained.

Key idea summary (for exam use)

• Correct option: (b) – Battery maintains potential difference across the circuit.​

• Battery: Provides emf, raises potential energy of charges, and drives current.​

• Resistor: Opposes current and converts electrical energy into heat or other forms.​

• Charges: Mostly already in the conductor; the battery moves them by electric field, it does not primarily “supply” them.​