What three explanations have been given for the collapse of the mayan civilization

Maya historians have generally settled on a combination of three main factors which could have caused the Maya collapse: warfare between city-states, overpopulation, and drought. The factors were not always contemporary or found all together in a single city.

Explanation:

although world war i began in 1914, the united states did not join the war until 1917. the additional firepower, resources, and soldiers of the u.s. to tip the balance of the war in favor of the allies. remaining neutral. when war broke out in 1914, the united states had a policy of neutrality.