Explain, why Native American populations reduced to one-fifth of its pre-Columbian numbers. OR Define the Columbian exchange. Give a detailed description of the phenomenon. Please include examples of things exchanged from the “Old” to the “New” World and vice versa.

Because of people coming into the "New World

Explanation:

We know that a lot of people wanted to go to the new world to be free and maybe even to figure out who are patriots and who aren't also at the first colony plymoth was made because of the question of releigion but that is another thing so because of all of the new people all of the Native American started reducing population.

the real answer is b

the answer is a. harriet tubman was a nurse on the battlefield.