Direction: Read these sentence to find out whether there is any grammatical mistake/error in. the error if any, will be in one part of the sentence .Mark the part with the error as your answer. If there is no error,mark 'No error' as your answer. (Ignore the errors of punctuation,if any)

You may not know it (a)/ but this engine is (b)/ claimed to have twice (c)/ as powerful as the previous one. (d)/ No error (e)

[SBI (PO), 2003]