Assertion : A hollow shaft is found to be stronger than a solid shaft made of same material. Reason : The torque required to produce a given twist in hollow cylinder is greater than that required to twist a solid cylinder of same size and material.

• Correct answer
  A

  If both assertion and reason are true and reason is the correct explanation of assertion
• 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: 'A'.