The subject line is used to ____. 

A. describe the contents of the letter in detail
B. include the names of other people who will receive copies of the letter
C. contain the writer's name and business
D. address the person to whom the letter is being written
E. bring the subject of the letter to the reader's attention

E. bring the subject of the letter to the reader's attention
The subject line is used to bring the subject of a letter to the reader's attention.