Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. The letter of that part is the answer. If there is ‘No error’, the answer is (5). (Ignore errors of punctuation, if any). Addressing of stubble burning, which (1)/ is a problem only in mid-November, (2)/ is easier than tackling road dust, which (3)/ is a perennial problem all through the year. (4) No error (5)