Find out which part has an error and mark it as your answer. If there is no error, mark ‘No error’ as your answer. Had I realized your house (A) was such a long way off, (B)/ I would take a taxi. (C)/ No error. (D)?

Option 3 : C

The correct answer is C

• The given sentence is a conditional sentence. 
• Conditional sentences are used to express that the action in the main clause (without if) can only take place if a certain condition (in the clause with if) is fulfilled.
• If the 'if clause' is in the past perfect tense, the following structure is followed:
  • If + Sub + had + v3.............would have + v3
                    (OR)
  • Had + Sub + v3.................would have + v3
• According to the rule given above, 'would have' will be used instead of 'could have'.
   

Correct Sentence: Had I realized your house was such a long way off, I would have taken a taxi. 

• The past perfect tense is used to talk about actions that were completed before some point in the past.
• 'Had + v3' is used in the past perfect tense.​ 
  • E.g. I had met him before the event.