Which type of letter is suitable for personal correspondence within the Department of Defense (DOD)?

The correct answer is a business letter. Within the context of personal correspondence in the Department of Defense (DOD), a business letter format is generally appropriate. This format allows for a structured way to communicate while maintaining professionalism, which is essential in a military environment. It typically includes a formal salutation, a clear purpose, and a closing that reflects respect and courtesy, which aligns with the standards expected in DOD communications.

In contrast, while an official letter is typically used for formal governmental, military, or organizational communications, it may not be suitable for personal correspondence due to its rigid structure and tone. A casual letter, characterized by an informal tone and layout, would not be appropriate in a professional setting like the DOD, where even personal correspondence often maintains a degree of formality. A standard letter is more of a general format used for various types of correspondence but does not specifically address personal exchanges within the DOD context. The business letter format strikes the right balance between professionalism and personal touch, making it the best choice for such correspondence.