Final answer:
Double parentheses in writing are typically used to indicate an external reference, meaning they set off nonessential, supplementary information rather than emphasizing the enclosed text. They serve to inform the reader without drawing significant attention away from the main narrative or argument. Option 2 is the correct answer.
Step-by-step explanation:
Double parentheses, also known as double voices in text, are used to convey different levels of narrative or information. While dashes may be used to emphasize content within a sentence, parentheses traditionally serve to downplay the content. Instead of drawing attention, they help to set off nonessential material such as additional information, clarifications, dates, or sources, indicating to the reader that the material inside the parentheses is not central to the main sentence but is supplementary.
For instance, in plays or books, stage directions or comments meant to provide additional context but not to be spoken or emphasized in the main narrative are often enclosed in parentheses. Similarly, in academic writing, parenthetical citations are placed at the end of a sentence containing a quotation or reference to indicate the source without interrupting the flow of the author's main argument.
Based on the conventional use of double parentheses in writing, the correct option is Option 2: An external reference. Double parentheses indicate a reference to additional, often nonessential, information that the reader may pursue but which is not the focus of the primary text.