Which of these phrases best describes a uniting principle of the progressive era

When conducting research for forming a hypothesis, which practice should historians follow?

What were the purposes of salt? check all of the boxes that apply. -to achieve peace -to protect the security of the united states -to form an alliance against communist nations - to stop the nuclear arms race - to give the united states an advantage over the soviet union

Brainliesttt !me : ) how did the world react to liberalization measures from the soviet union?