Answer : Option D

Explanation :

There are three components of a Mail Merge:
The main document controls the merge. It contains the fixed information that will be in every letter and the merged codes where the variable text will be.
The data source is a document or database that contains the information that will be different for each letter. Remember, the data source is usually the names and addresses. It can be stored in a table in Word, an Excel Spreadsheet or a table in Access.
The merged document is the result of a merge. These are the individual letters that result from the merge. The merge fields are replaced with the actual data from the Data Source file.