Boolean data represents a logical value with only two possible states, typically true or false. In Information Technology, Boolean types are foundational for conditions, comparisons, control flow, and database fields that store yes-or-no style information. The example, "Whether a number is positive or not," fits Boolean data because the statement can be evaluated as true if the number is greater than zero, or false otherwise. This two- state characteristic is exactly what defines Boolean logic. The other options describe different data types: the first letter of a last name is a character, a full last name is a character string, and the price of gas in dollars and cents is numeric with decimals, typically stored as a floating-point or fixed-point decimal type. Boolean fields are widely used in systems for flags such as active or inactive, approved or not approved, and eligible or not eligible. Therefore, the correct example of Boolean data is whether a number is positive or not.