Option C. Columbus underwent deep voyages and discovered the present day America. He also discovered the marine route which associated the old Eastern world to the new Western world.
After the establishment of Sea route there was 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 also initiated the arrival of dangerous diseases too and major part of the European, native American and Asian population died causing shortage of human labor, this gradually lead to the slavery of Africans.