During the columbian exchange, which way did plants, animals, diseases flow?

question 2 options:

from both north to south and south to north

from west to east only

from both east to west and west to east

from east to west only

Primary sources are usually  more accurate and are written by someone who experienced it or witnessed it. secondary sources are those who heard of it after the fact that can lose details and or twist the event in a light that benefits them.