HELP GIVING BRAINLIEST AND 100 POINTS How did migration lead to the population of the world?

What is one reason the united states had a two party system

In shifting to a defense policy based upon the concept of "flexible response," president kennedy was indicating that he had grave doubts about thevalue of which previous defense policy? a massive retaliationb collective securityc containmentd air power

Which statement best describes the response by the united states and its allies to the berlin blockade? planes dropped tons of supplies around the city each day. trucks smuggled tons of supplies into berlin about once a week. tons of supplies were delivered to west berlin by boats. tons of supplies were purchased from east berlin each day.