Which of the following is a primary source that could be used to learn about the american civil war?
a. letters from soldiers to their families
b. an encyclopedia's summary of the civil war
c. folktales from battles
d. a biography of general robert e. lee

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.