Which of the following will give zero current through the resistor of 2 Ω.

The correct answer is Option (2) → 

Option (1): In this circuit, the diode is oriented such that it becomes forward biased with the given battery connection, allowing current to pass through the circuit. Since a conducting path exists, current flows through the 2 Ω resistor and hence this option does not give zero current.

Option (2): The two diodes are connected in series but in opposite directions. For the given battery polarity, one diode is forward biased while the other is reverse biased. The reverse-biased diode blocks the path, so the circuit remains open. Hence, no current flows through the 2 Ω resistor.

Option (3): Here, the two diodes are connected in parallel and oriented in the same direction, so both become forward biased for the given polarity. This provides an easy conducting path for current, allowing it to pass through the resistor, so the current is not zero in this case.

Option (4): In this case, the diodes are connected in parallel but in opposite directions. For any given polarity, one of the diodes will be forward biased and will allow current to flow through its branch. Since a conducting path is available, current flows through the resistor and this option also does not result in zero current.