What is the most important to know about the columbian exchange and why

I'll just give you ten fun facts, and let you choose.
#1 - Before the Columbian Exchange, the old world hadn't seen a tomato.
#2 - Old world animals expanded food supply in the new world.
#3 - Horses changed the lifestyle of many Native American tribes.
#4 - Many Native American tribes were wiped out due to the trade.
#5 - Smallpox in the new world was deadlier than the Black Death.
#6 - Columbian Exchange increased population in the old world.
#7 - New world crops became popular in old world.
#8 - Ireland became so reliant on potatoes, it let to the great potato famine.
#9 - Columbian Exchange let to the Atlantic Slave Trade.
#10 - Columbian Exchange let to the extinction of many species.

C. equitable; undue influence