The song dynasty succeeded in a. reunifying several kingdoms b. reunifying all the tang territory c. breaking up several kingdoms d. breaking up all the tang territory.

to reform the distraught soviet union, the democratization of the communist party was promoted through party secretary mikhail gorbachev's policies of “perestroika” and “glasnost.” perestroika refers to the reconstruction of the political and economic system established by the communist party.

they became hereditary because there weren't many jobs for people in lower classes