A result of Jazz's development during the 1920s and the 1930s was that many people embraced jazz music. Option D is correct.
It is believed that African American musicians were the founders of Jazz. When Jazz spreaded, it reached the American middle class.
Jazz is considered a blend of African American traditional music along with white middles class society's traditions. Jazz culture significantly increased in American citiies such as New York and Chicago, there, several jazz musicians, particularly black musicians, used to playe in jazz clubs.
Roosevelt is telling the American public that maintaining an isolationist policy amidst the war will not protect them. All the freedoms that he listed on his speech would be threatened by the march of the Axis powers and it would be a matter of time when they have to confront this threat.
