A jet stream forms high in the upper troposphere between two air masses<span> of very different temperature. The greater the temperature difference between the air masses, the faster the wind blows in the jet stream.
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So "Differences in temperature between two air masses" is the answer
According to scientists, many years ago their was a supercontinent called "Pangaea." As years went by, the continents slowly drifted apart which is what's today. However, from recent discovers, scientists predict that in about 250 millions years from now the continents will merge again, however this time, in a different order ("Pangaea Ultima"). So the answer to your question is D.
Hope this helps. :D
I think its B but I'm not sure .. sorry
