DIRECTIONS for the question: Read the sentence to find out whether there is any grammatical error or idiomatic error in it. The error, if any, will be in one part of the sentence. The number of that part is the answer. if there is 'No Error" the answer is (E). (Ignore errors of punctuation if any.)
The manager tried hard to effect a change in company policy, but the owner, who steadfastly refused to compromise, overruled him on every point. No error.