Final answer:
The minimum size for a domestically accepted letter is 6 x 4 inches, and letters are typically formatted on 8 1/2 x 11" white paper with 1-inch margins.
Step-by-step explanation:
The minimum size for a domestically accepted letter according to the United States Postal Service (USPS) is option B) 6 x 4 inches. This size is considered to be the minimum dimension for a piece of mail to be processed through the USPS's automated equipment.