Under the rule described by Whren v. United States, a routine traffic stop remains valid if there is probable cause to believe a traffic violation occurred, regardless of the officer's subjective motive.

• A. Reasonable suspicion
• B. Consent
• C. Probable cause to believe a traffic violation occurred
• D. A court warrant

Answer: (C)

Under Whren, the key idea is that a routine traffic stop is valid if the officer has probable cause to believe a traffic violation occurred, and the officer’s subjective motives do not matter. The stop is judged by an objective standard: if there is probable cause that a traffic violation happened, the seizure is allowed, even if the officer’s real purpose was something else. This means the correct choice describes the exact basis for the stop: probable cause to believe a traffic violation occurred. The other options don’t fit because reasonable suspicion is too low for a full stop, consent would authorize a stop but isn’t the standard Whren relies on, and a court warrant isn’t required when probable cause exists for a traffic violation.