The first-past-the-post electoral system explains a. why the united states has only two major parties b. why republicans have conservative candidates c. why democrats have liberal candidates d. why the united states has coalition governments

The correct answer is A. why the United States has only two major parties.

Indeed, there is even a name for this principle in political science and it is known as Duverger’s law. In first-past-the post systems a voter casts his vote and the candidate with the  most votes becomes the winner of the seat. This means that only the party that arrives first or second will receive seats while the party that arrives third will get no seat at all.

answer; i believe that the correct answer is (c) arctic tundra;

polisit can also mean a body of citizens. in modern historiography, polis is normally used to indicate the ancient greek city-states, like classical athens and its contemporaries, and thus is often translated as "city-state". the body of citizens came to be the most important meaning of the term polis in ancient greece.