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.
Ridges, Ridges are elevated boundaries that divide watersheds
The Ice Ages shaped and sculpted the face of the Earth. Continents that were once connected by land bridges had shifted and separated during the Ice Ages. Therefore without the Ice Ages, Earth would look significantly different, and some of the natural beauties like Niagra Falls would not exist.
I'm not 100% sure... but I would say B.
People should learn about the currents, waves, and tides just in case of an emergency or the tides are too high. The people should know if their worried about their structure of their home, or worried about their safety.
