Which developments most led to changes in the level of presidential power during the 20th century? a. congress's decision to override nearly every presidential veto b. state governments' demands for greater independence from the federal government c. presidents' increasing use of military force without congressional declarations of war d. the supreme court's decision that the war powers act was unconstitutional

C is the correct answer.

In previous generations, Congress unquestionably held the power to declare war. During World War II, the United States was repeatedly lobbied by the British to get in the war earlier but did not get in until after Pearl Harbor because of a lack of Congressional support.

Our current model lets the President take the lead and we've seen an increase in the use of military actions without Congressional declarations of war.