How did some formerly enslaved african americans in the south respond to advancing union forces

They served as scouts and spies for the union

The correct answer is African Americans served as scouts and spies for the Union.

During Civil War African Americans often played the role of spies, according to William Stroke’s Account of his War Record over 90% of the Union War Force consisted of African Americans. They could not be in the battlefield because of lack of experience and poor training but they worked behind the scenes as scouts, raiders or spies, they provided the Union advantages.

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.