Read the sentence to find out whether there is an 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 (5). Ignore errors of punctuation, if any. 

Not only the student (1) / but also her parents (2) / was enjoying the virtual orientation session (3) / at the class yesterday. (4) / No error (5)