Letters are used to address whom?

The correct choice indicates that letters are used to address individuals outside the department or agency when a personal tone is appropriate. This reflects an important aspect of business communication, where letters serve as a formal yet personal means of conveying messages to external parties. In many cases, letters can establish a connection, express gratitude, convey requests, or provide information in a manner that feels more personal compared to other forms of communication, such as emails or memos.

Using letters in this context can enhance the relationship between the organization and individuals in the external environment, making it a preferred option when the intent is to foster goodwill or maintain a warm rapport. Additionally, a letter's physical format can denote importance and formality, making it an appropriate choice for conveying sincere intentions to recipients outside the organization.

On the other hand, while addressing individuals within the department or agency may also require a formal communication style (as in the first option), the personal touch is typically conveyed through more informal channels, like emails or internal messages, rather than letters. While technical communications may be necessary with external agencies, letters are generally less about technical exchanges and more about personal or formal correspondence. Lastly, addressing only high-ranking officials in the military does not capture the broader purpose of using letters, which is not