The sentences are divided in three separate parts and each one is labelled A, B, C. Read each sentence to find out whether there is an error in any part. No sentence has more than one error. You may feel that there is no error in a sentence. In that case, D will signify a 'No error' response. Error may be in grammar, word usage or idioms. There may be a word missing or there may be a word which should be removed. You are not required to correct the error. You are required only to indicate your response on the answer sheet. (A) I do not know/(B) what is he doing/(C) to solve the problem. /(D) No error

• A

  Part A
• Correct answer
  B

  Part B
• C

  Part C
• D

  No error

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