Which of the following is one of the reasons that the native american population decreased significantly in north and south america after the arrival of the europeans?

a.
many native americans moved to europe.

b.
the europeans brought diseases like smallpox, and many native americans died.

c.
native american tribes fought against each other in wars.

d.
there was widespread famine, and many native americans starved.

B.The Europeans brought diseases like smallpox, and many Native Americans died.

Explanation:

A very good example of that is when the spanyards arrived to Mexico to conquer the Aztecs, they brought small pox from cuba, where it had already attacked part of the native population, it´s very important to notice that diseases like this are particularlly succesful when facing virgin populations, this means societies where there are no antibodies against them, this decimated heavily the native american population.