I believe the answer is D. polar;subtropical.
In the Northern Hemisphere, the<u><em> polar </em></u>jet stream brings cold weather conditions from the north, and the<u><em> subtropical </em></u><em />jet stream brings warm weather conditions from the south.
I hope this helped!
Extinction and speciation rates.
It is c commensalism that's the answer lol I can't spell it
Answer:
Gel Electrophoresis.
I took the Khan academy test :)