Assertion : A spark occur between the poles of a switch when the switch is opened. Reason : Current flowing in the conductor produces magnetic field.

• A

  If both assertion and reason are true and reason is the correct explanation of assertion
• Correct answer
  B

  If both assertion and reason are true but reason is not the correct explanation of assertion
• C

  If assertion is true but reason is false
• D

  If both assertion and reason are false.

Hence, the correct answer is option: 'B'.