Which statement best explains how the constitution addressed a weakness in the articles of confederation?

a. states were able to make individual trade agreements with foreign countries, so the constitution made it illegal for a state representative to meet with a foreign diplomat.

b. the federal government was inefficient because its power was divided into three branches, so the constitution created a single federal government office led by the president.

c. state militaries were more powerful than the federal army, so the constitution required each state to send a percentage of its population to defend the country.

d. the federal government did not have enough power to enforce its laws, so the constitution gave the federal government more power than the states.