Device which helps in maintaining a potential difference across a conductor is
(A) A cell
(B) A battery
(C) Both
(D) None

Hint
Potential difference can be defined as the difference in the amount of energy that charge carriers have between two points in a circuit. The potential difference is measured in volts and is also known as voltage. The potential difference between any two points is defined as the amount of work done in moving a unit charge from one point to another.

Complete step by step answer
A battery consists of a group of cells to produce a potential difference. A cell is a single unit that makes a battery. A group of cells makes a battery.
Both battery as well as a cell help in maintaining a potential difference across a conductor. This makes the current flow. They are used as a portable source of power in almost all electric devices like flashlights, mobile phones, and electric cars.
Hence option (C) both is the correct answer.

Additional Information
An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. A battery is a device consisting of one or more electrochemical cells with external connections for powering electrical devices such as flashlights, mobile phones, and electric cars.

Note
In a conductor, electrons flow only when there is a difference in electric pressure at its ends. This is also called potential difference, it is the difference in potential between two points that represent the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other.