PLEASE HELP DUE TODAY!! Why would a war expand from just a couple of countries to a world war?

World Wars are born by at least 2 countries fighting and then ask for alliances such as the U.S. had an alliance with Mexico when world war 2 occurred. Therefore to make it a world war, all of the countries chose a side or made a new one.

" During World War II, Mexico played a significant role in the Allied effort. Everyone knows the World War II Allied Powers: the United States of America, the United Kingdom, France, Australia, Canada, New Zealand...and Mexico?

That's right, Mexico. In May 1942, the United States of Mexico declared war on the Axis alliance. They even saw some combat: a Mexican fighter squad fought valiantly in the South Pacific in 1945. But their importance to the Allied effort was much greater than a handful of pilots and airplanes. " ThoughtCo.

<3 Enjoy,

    Dea

a nationwide discount program is implemented.

explanation:

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.