The author of The Prince was a) Niccolo Machiavelli. The Prince is known to be one of the first works of modern philosophy, specifically political philosophy. The book circles around the theme of a prince's pride and glory overshadowing what he should be doing for the general good of the people and puts into context the question of "Does the end justify the means?"
Frederick Jackson Turner was an American historian that defended that the strength and the vitality of America’s identity lay in its land and vast frontier.
He said that the vast frontier was very important for an - then young - country like America. He also said that America should always seek new frontiers abroad.
This changed people’s idea and America identity, this led the US to call for new frontiers like in Cuba, Philippines, Puerto Rico, and Guam.
Because of this growing frontiers, America became a diverse country with different countries and tolerant social mix, America is a safe place for many races and religions, all because of its frontiers.
It become a concern of the military planners due to the high casualty the marines suffered during the taking of Iwo Jima. Also the battle proved that even though the battle was an American Victory the Japanese army is prepared to die defending and willing to wage a suicide attacks even though they already know that they lost the war. That also attacking the Japanese Home Islands would be a costly attack of lives of american soldiers and the new strategy develop in Iwo Jima would be an arduous battle if the Americans would invade the Japanese Island with the Japanese people that is already to prepare to die fighting.
AFRICA is the correct answer to this question