Directions: Read the sentence carefully to find out whether there is any grammatical error in it. The error, if any, will be in one part of the sentence. The number of that part will be the answer. If there is no error, the answer is (5).

The head of the department, along with his colleagues (1) / are coming to attend (2) / the conference which is (3) /scheduled this afternoon (4). / No error. (5)