Answer:
B I think I'm very sorry if it's wrong
Europe TL;DR: For reasons beyond human control, rooted deep in the divergent evolutionary histories of the continents, the Columbian Exchange massively benefited the people of Europe and its colonies while bringing catastrophic crumminess to Native Americans.
Collective security is when basically multiple groups/nations form a coalition together and agree to not to attack each other, and to help defend from one another or from another threat.