21. Why is the Columbian Exchange an example of diffusion? a. The native population dramatically declined.

b. The Appalachian Mountains were difficult to cross.

c. New foods and products were brought to Europe and the Americas

d. Independence was declared in 1776.

c. New foods and products were brought to Europe and the Americas

Explanation:

Ideas, goods, and products were exchanged around the world, spreading to new lands, which is what diffusion is.

Correct answer is c. New foods and products were brought to Europe and the Americas .

Explanation:

Option C is the only example of diffusion in here and therefore is the only correct answer. New cultures that were exchanged totally changed the diet of people and additionally increased their health and life expectancy.

A is not correct as this is one of the bad consequences of Age of Discovery.

B is not correct as the natural barriers are not the example of diffusion.

C is also not correct as Independence of US was declared because of wrong colonial policy of Great Britain.