In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
Students of marketing know that the term Unique Selling Proposition, or USP was developed in the 1940s in the United States. USP is (1) ______ as the true value (2) ______ a firm. At the core of (3) ______ successful business, there is (4) ______ a value proposition, something (5) ______ promoters and the managers are proud of.
Select the most appropriate option to fill in blank No.4.