Which of the following was a major reason the united states exchanged neutrality for war in 1917?
a. americans felt it was their duty to come to the aid of the central powers, who were being badly beaten.
b. the germans had taken over a vital trade route between britain and the united states.
c. the germans massacred the entire population of a major british city, including civilians.
d. the germans used their submarines to attack ships carrying american citizens and supplies to the allies.

i am sure the answer is d

in mcculloch v. maryland (1819) the supreme court ruled that congress had implied powers under the necessary and proper clause of article i, section 8 of the constitution to create the second bank of the united states and that the state of maryland lacked the power to tax the bank.

gibbons v. ogden, (1824), was a landmark decision in which the supreme court of the united states held that the power to regulate interstate commerce, granted to congress by the commerce clause of the united states constitution, encompassed the power to regulate navigation.