Evidence seems to suggest that the art of metallurgy began in
asia
middle east
africa
north america

 The Middle East

Bronze Age developments in metallurgy are traced back as far as approximately 3000 BC in the region between the Tigris and Euphrates rivers in what is today called the Middle East.  

There also were developments of metallurgy in Africa, which came at a later date.  Bantu-speaking peoples migrated from Western Africa (in the area of modern Nigeria) throughout southern parts of Africa starting around 1000 BC and continuing to the 1500s (or perhaps a bit later, by some accounts).   The Bantu developed metallurgy practices that they brought with them throughout the regions where they migrated.  There is some debate among historians as to whether iron metallurgy in Africa arose independently or was learned or borrowed from the Middle East.

i believe the correct answer is option b. most eastern european nations joined nato.

though i could be wrong, option d. the eastern european nations were granted complete independence, would be another choice.

hope this ! : )