Read the sentence below to find out whether there is any grammatical error in it. The error, if any, will be in one part of the sentence. Choose the option with that part as your answer. If there is no error, choose 'D' as your answer. (Ignore the errors of punctuation, if any).
He wanted to work all night but we saw that he was completely worn out and so we persuaded him to stop.
He wanted to work all night
but we saw that he was completely worn out
and so we persuaded him to stop.
No error.
Correct answer is B
but we saw that he had completely been worn out