Which document type is typically used to correspond with individuals or agencies outside of the organization?

The correct choice is letters, as they are the standard format for official correspondence with individuals or agencies outside of the organization. Letters are formal communications that can convey important information, requests, or responses in a professional manner. They provide a record of the communication and are usually formatted in a way that is recognized and respected in business and legal contexts.

In contrast, incident reports are generally used for internal documentation of events or occurrences and are not typically employed for external communication. Memos, while they serve as internal communication tools, are meant for sharing information within the organization rather than with outside parties. Company journals serve more as records of activities or observations over time and are not designed for direct communication with external entities. Thus, letters are the most appropriate choice for corresponding with those external to the organization.