To answer this question, let's analyze each option:
Option A) heading - This word is associated with the structure of a document or a section. It typically represents the title or a section title within a document.
Option B) body - This word is associated with the main content of a document or a section. It represents the bulk of the information or the main text.
Option C) letter - This word is different from the others because it does not relate to the structure or content of a document. Instead, it refers to a written message or correspondence.
Option D) closing - This word is associated with the end or conclusion of a document. It can represent the final remarks, farewell, or a signature block.
The correct answer is C) letter. This option does not belong with the others because it does not relate to the structure or content of a document like the other options do.