The exchange permanently changed the natural and human environments
Explanation:
Columbus underwent deep voyages and discovered present-day America. He also discovered the marine route which associated the old Eastern world to the new Western world.
After the establishment of the Sea route there was an exchange of goods with other countries started. But the negative impact was that people of Eurasia were not healthy with high levels of immunity.
The interchange of food supplies initiated the arrival of dangerous diseases too and a major part of the European, Native American, and Asian population died causing a shortage of human labor, this gradually leads to the slavery of Africans.
Alliances provide mutual support in the event of an attack; protecting security of entire regions; providing framework of military security through organizations such as NATO.
