Which of the following is an example of the effect of the bubonic plague on the behavior of medieval europeans?

Which of these did the soviet union do in 1961? it built a wall through berlin to keep people from moving to the west. it used force to destroy a wall the united states had built in berlin. it convinced the british and french to merge their zones in berlin with the soviet zone. it threatened to bomb berlin if the united states did not leave within 30 days.