Read the sentence to find out whether there is any error in it or not. The error, if any, will be in one part of the sentence. The number of that part (which has the error) is the answer. If there is no error, the answer is (5). Ignore errors of punctuation, if any.

Language is (1)/ often used for one of (2)/ the following three purpose, (3)/ namely to inform, to convince and to persuade. (4)/ No error (5).