A.
This was a method the US used to try stay out of the war.
They did not want to be dragged in a costly war; and they were able to benefit from the production of those arms being sold. Mostly the US said that they would sell arms to any country that deemed vital to the "defense" of the United States.
World War I, the United States was trying to distance itself from events in Europe (and in the Pacific). The country was not yet ready to participate in another war, but it did not want to just let Fascist dictatorships take control of the whole of Europe, either. The Lend-Lease Act did, essentially, end U.S. neutrality by agreeing , but American troops would not be committed until after Pearl Harbor late in 1941. meaning the correct answer is let England borrow weapons in the early 1940s.
1. Superior Weapons. Spanish weaponry was far superior to anything used by the Aztecs or Incas.
2. Alliances and Experience. The invading Spanish forces also took advantage of internal divisions within the Aztec and Inca empires.