Automobiles became increasingly popular because of

D) Ford’s revolutionary use of the assembly line to make less-expensive cars.

Explanation: I'm honestly not 100% sure this is the answer, but I know it's not C. This should be the answer, and if it's not, it's A. But answer D first.

the united states has a federal government. the president is the head of the federal government of the united states. however, each state forms its government for administration purposes. the powers of the state governments are exercised within restricted state boundaries. and citizens participate in this government by voting.