Why did the geography of the Americas and Eurasia produce such different results?

The continents that are spread out in an east-west direction such as Eurasia,had a developmental advantage because of the ease with which crops, animals,ideas and technologies could spread between areas of similar latitude.

crop rotation kepy different plants in the soil instead of once constintly. when switching out plants you have different nutrients being absorbed at different speeds and different roots growing differently therfore the spoil and water flow have to adapt and carry fresh nutrients to carry the constant changes that were going on in the soil.

c, because the american revolution was from 1765 to 1783.