Which of these is most responsible for differences from the twentieth century to the twenty-first century?
a. fuel-efficient automobiles
b. low-cost computers
c. solar heating devices
d. student writing skills

Which of the following problems did shays rebellion show about the articles of confederation? a. there was no federal standing army b. states couldn’t create their own tax laws c. the federal government imposed too many taxes on states d. there was too much federal regulation of interstate commerce