How did farming make civilization possible in americas

i think the answer is c, rivers.

explanation:

sometimes, borders fall along natural boundaries like rivers or mountain ranges. for example, the boundary between france and spain follows the crest of the pyrenees mountains. for part of its length, the boundary between the united states and mexico follows a river called the rio grande. the borders of four countries divide africa’s lake chad: niger, chad, cameroon, and nigeria.

soviet influence spread across eastern europe sharply during and after wwii. the soviet armies liberated the countries in eastern europe and occupied them from the germans as they were forced to retreat towards germany.