Ука­жи­те номер под­черк­ну­то­го фраг­мен­та, в ко­то­ром до­пу­ще­на ошиб­ка.

Since the illegal transfer (1) of digital music via the Internet (2) has become widespread, many songwriters and performers have become worrying (3) that their main source of income will come to an end (4).