Which of these was a negative result of the comlumbian exchange

The primary positive effect of the Columbian exchange was the introduction of New World crops, such as potatoes and corn, to the Old World. The most significant negative effects were the transmission of African populations into slavery and the exchange of diseases between the Old and New World.

Explanation:

i think it should be slowed colonial western march

a big wall across the mexican border so no drugs, terrorist, or illegal immigrants can come through : )