Which of the following is an identifiable source?

An identifiable source is one where the information can be traced back to a specific individual who can be held accountable for the information they provide. In this case, an accomplice providing a confession is a prime example of an identifiable source. This is because the accomplice not only directly shares information related to their involvement in a crime but can also be identified by law enforcement. Such confessions are typically accompanied by a sense of accountability, as the individual may face legal consequences for their testimony.

In contrast, other options do not represent identifiable sources in the same manner. An anonymous tipster does not reveal their identity, making it difficult to verify the information or follow up with the person if necessary. An online post, while potentially traceable in some cases, does not offer a firm link to a specific individual if the identity behind the post is not verified. Similarly, an unknown citizen wandering the street lacks any identifiable traits or context that would provide reliable information, as this person may not be connected to any relevant events or actions related to a case. Thus, the accomplice providing a confession stands out as the most reliable identifiable source in this scenario.