A historian reviews several of his colleagues' books about early African states. He then writes his own book
summarizing the findings in these works and offering his
own opinions on their significance.

demand is the need and oportunity to buy a given good or service.

a is the final : )

if the government does something the people dont like i tihnk threre would be a revolt

you didn't list the options. however, a few communist countries today are: the people's republic of china, north korea, and cuba.