Answer:
The body
Explanation:
The body is the longest part of a document or letter and is generally split into three  sub-categories: introduction, key material and description. Â
The introductory section specifies the letter's purpose. Â
The key material contains all the specific information needed and does not have any  fixed duration specifications.
The last section sums up the information given, Â reaffirms the purpose of the document.