between Europe and Asia (dividing Eurasia): along the Turkish Straits, the Caucasus and the Urals (historically also north of the Caucasus, along the Kuma–Manych Depression or along the Don River) between Asia and Africa (dividing Afro-Eurasia into Africa and Eurasia): at the Isthmus of Suez.
I would say the answer is A. (Plebs) :)
Nitrogen (78%), Oxygen (21%), Argon (0.9%), and the remaining 0.1% consists of traces of neon, krypton xenon, carbon dioxide, nitrogen oxides, and traces of others. so Nitrogen is the greatest. I hope this helps :)
