If those things come to pass in other parts of the world, let no one imagine that america will escape, that america may expect mercy, that this western hemisphere will not be attacked and that it will continue tranquility and peacefully to carry on the ethics and the arts of civilization. Why is Roosevelt's refutation effective?

ARoosevelt already knows that Japan and Germany are planning to attack the United States.
BRoosevelt already knows that his audience has already lost any and all hope of avoiding conflict.
CSome of Roosevelt's audience does imagine that America can escape or avoid aggression.
DRoosevelt already knows that people make good choices when they are motivated by fear.

This speech was given in Chicago, in 1937, 2 years prior to the WWII but the international tension was already beginnig to be a problem, Germany was already heavily armed and Italy was doing the same, while Pearl Harbor didn´t happen till 1941, Roosevelt was preparing the american people for the inevitable, he knew the fight will eventually grow larger than only Europe and Asia, and that the gorvernment of the US will play a significant role in the outocme of the war.