What is most responsible for differences from the 20th century to the 21st-century

thomas jefferson is the answer

your answer would be (b)

roosevelt, a progressive reformer, earned a reputation as a "trust buster" through his regulatory reforms and anti-trust prosecutions. his "square deal" included regulation of railroad rates and pure foods and drugs; he saw it as a fair deal for both the average citizen and the businessmen.

taxation that is paid in kind, that is with goods or services rather than money