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)

We are trying to (a)/ find out the root cause (b)/ of this recurring problem (c)/ since the last four days. (d)/ No error (e)

[SBI (PO), 2000]