Answer:
a
Explanation:
After Columbus’ arrival in the Americas, the animal, plant, and bacterial life of these two worlds began to mix. This process, first studied comprehensively by American historian Alfred Crosby, was called the Columbian Exchange. By reuniting formerly biologically distinct land masses, the Columbian Exchange had dramatic and lasting effects on the world. New diseases were introduced to American populations that had no prior experience of them. The results were devastating. These populations also were introduced to new weeds and pests, livestock, and pets. New food and fiber crops were introduced to Eurasia and Africa, improving diets and fomenting trade there. In addition, the Columbian Exchange vastly expanded the scope of production of some popular drugs, bringing the pleasures — and consequences — of coffee, sugar, and tobacco use to many millions of people. The results of this exchange recast the biology of both regions and altered the history of the world.
