Which of the following is a direct identifier?

• A. Race
• B. Date of birth
• C. Passport number
• D. Quasi identifiers

Answer: (C)

A direct identifier is information that can identify a person by itself. A passport number fits this because it’s a unique government-issued number tied to a specific individual, so it alone identifies who that person is. Race and date of birth describe attributes but don’t single out one person—many individuals can share the same birth date or belong to the same race. When such attributes are combined with other data, they can help identify someone, which is what quasi identifiers refer to.