Disagreement marks historical appraisals of America' s emergence as a great power at the turn of the twentieth century. On the one hand, historians have praised the maturing of the Republic, which was now able to take its place among the arbiters of the world' s destinies. On the other hand, many writers have tried to define America' s new floe indistinctive terms. They argue that the United States did not enter the great power game as just another player but introduced a new style. of diplomatic play and perhaps even a new set of rules.
Judgments clash about these innovations. An older school of thought stresses the idealism that America brought to the world arena. More recently, "New left" revisionists have charged that America' s contribution to international life was the self-serving notion of "informal empire," typified by a worldwide Open Door doctrine. This strategy avoided formal territorial possession but sought economic dominance of foreign raw materials, markets, and investments.
Historians disagree further about the motivating impulses of American diplomacy. Recent "revisionists" have tended almost exclusively to emphasize domestic economic factors in explaining American foreign policy, the United States sought foreign markets, the argument goes, to solve the problems of domestic overproduction and constant business depressions. Other scholars respond that international politics can only be properly understood in an international con- text. They argue that Theodore Roosevelt, for example, acted not for narrow domestic reasons but because he realistically perceived that if the United States did not hold its own against the other powers, it would soon risk being eclipsed on the world stage, and even being pushed around in its own hemisphere, despite the Monroe Doctrine.
By saying that the U.S. "was now able to take its place among the arbiters of the world' s destinies" (the second sentence in paragraph 1), the author means that the U.S. ______.

A. established itself as one of the big powers
B. was now directing the world on a new course
C. became mature as a nation
D. brought new rules to the world' s diplomatic play