Final answer:
An 'unknown risk' stop refers to a situation in which a police officer suspects that the driver may have a high potential for violence. It is based on the officer's reasonable suspicion of criminal activity and allows the officer to detain and frisk the suspect for weapons.
Step-by-step explanation:
An 'unknown risk' stop refers to a situation in which a police officer suspects that the driver may have a high potential for violence. This type of stop is based on the officer's reasonable suspicion that the person has committed or is about to commit a crime. It allows the officer to detain and frisk the suspect for weapons if they believe the suspect is armed and dangerous.