Which of the following is a complete bibliographic reference?

A complete bibliographic reference provides all the necessary information that identifies and allows a reader to find a source. While the option "Source" may seem too vague initially, it can be understood in this context as a general term encompassing all parts of a bibliographic entry. A complete bibliographic reference typically includes details such as the author, title, publication date, publisher, and sometimes the URL or DOI for online sources.

The other options listed—title, URL, and author name—are important components of bibliographic references, but they do not represent a complete reference on their own. A title, for instance, tells you the name of the work, but without the author’s name, publication date, and other details, it cannot serve as a complete reference. Similarly, a URL points to an online resource but lacks context without additional information, like the creator and the title of the piece. Lastly, the author's name is critical for attribution but, by itself, does not convey enough information to locate or identify the work comprehensively. Thus, in the context provided, "Source" embodies the concept of a full bibliographic reference, as it can imply the collective information about a resource.