Which event happened in 1990? (from #6) Gorbachev signs decree ending the Union of Soviet Socialist Republics. Bulgaria’s Communist Party leader resigns; the country heads toward free elections. Poland’s communist government falls; Lech Walesa becomes president. Lithuania, Estonia, and Latvia gain independence from the Soviet Union.

It's C,  Poland’s communist government falls ; Lech Walesa becomes president.

Explanation:

president thomas jefferson commissioned the expedition shortly after the louisiana purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, and to establish an american presence in this territory before britain and other european powers

the hereditary right of a monarch to rule from the mandate of heaven