What will happen when an electric circuit is open?
A) Current will flow in each and every part of the circuit.
B) Current will not flow in any part of the circuit.
C) Current will flow in half part of the circuit.
D) Current will be minimum in the circuit.

Hint: Electrons cannot traverse or move through an open circuit and there is no current or 'electron' flow. If the electric circuit is left open then there will be an incomplete path to drift the electron in that case no drift velocity of the electron is observed, hence there is no flow of current in the circuit.

Complete answer:
Compare an open circuit with the 'potential' energy. Even though potential energy exists there is no kinetic energy unless the electrons have a path to take.
An open circuit does not provide such a path. Although ,the voltage may be present with an open circuit but it is the condition of doing no work.
The Kinetic energy \[(K.E)\] means something with mass is moving and in some cases that movement is harnessed to accomplish any kind of desired work.
Potential (Voltage) which is doing nothing because a circuit is open cannot accomplish any work since there are no electrons moving.
Another perspective of thinking is that :-
If an electric circuit is opened - the electricity flow stops.
This happens due to the fact that air is a strong insulator, and most amounts of electricity do not have enough voltage to overcome this resistance .
This is reflected in a formula voltage equals to current times the resistance.
Through this relationship, as resistance reaches a high level, voltage gets drop, and the electric current stops because it cannot overcome the resistance with the force of voltage or amps.

Hence option (B) is the correct option.

Note: As the ionization occurs much less voltage or potential is required to maintain the ionization path than is required to achieve ionization to start with.
For instance a car’s ignition coil is capable of producing \[40000 - 50000\] volts of electricity.
Yet when the voltage is measure at the end of the spark plug wire there will be only \[9000 - 10000\] volts due to the air or the fuel molecules being ionized