When should you spell out an acronym rather than using the abbreviation?

When should you spell out an acronym rather than using the abbreviation?

• A. If an acronym appears only twice or infrequently, spell out the term every time and avoid the acronym entirely.
• B. If an acronym appears frequently, use the acronym in all caps.
• C. Acronyms should only be used in the body, not in the subject line.
• D. Use acronyms interchangeably with the full term.

Answer: (A)