)in which case did the supreme court rule that in addition to the suspicion required to justify a stop, the officer must have reasonable suspicion that the person stopped is ʺarmedʺ and ʺdangerousʺ before a frisk can be conducted?

The correct answer is Terry v. Ohio, 392 U.S. 1 (1968),

In this case, the Supreme Court ruled that a police officer can stops a suspect on the street and frisks him or her without probable cause to arrest if there is reasonable suspicion that the suspect is armed.

chavez's example shows that nonviolent protest can work well. it shows that one nonviolent man can stop a mob, which proves chavez's point and persuades people to protest nonviolently.