A policy of avoiding political or military agreements with other countries

Isolationism.

Explanation: It’s basically where you just mind your own business. USA was an isolationist country until WWI pretty much.

companies sell stock to their businesses grow and become "public"

john maynard keynes developed new economic theories in response to the : b) great depression of the 1930s. his theories are so important that they are known as "keynesianism". in his works he supports the idea of a government with deeper involvement and intervention to end the great depression.