Final answer:
The most common element in the conclusion of a letter is thanksgiving or an expression of gratitude. It is typically included in the last body paragraph before a formal closing such as 'Sincerely,' and is followed by the writer's typed name with space for a signature.
Step-by-step explanation:
The most common element in the conclusion of a letter, particularly in a business or formal context, is thanksgiving. This typically manifests as expressing gratitude to the reader for their time or consideration. In the closing paragraph, you should briefly restate your purpose for writing the letter, mention the importance of the contents, and conclude by thanking the reader. After this final paragraph, you would conclude with an appropriate closing, such as “Sincerely,” followed by a comma, then leave two blank lines, and type your name. Your handwritten signature would go between the closing and your typed name.