1. A/An
is a form of government in which citizens
choose their leaders by voting.

A "Republic" is a form of government in which citizens choose their leaders by voting.

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

i think it was   tsar alexander ii