Look at the table Migrations of Homo sapiens
200,000 years ago
appear in Africa
40,000 years ago
arrive in Europe
20,000-60,000 years ago
?
15,000 years ago
?
Beginning with the earlier development, what events will replace the question marks in the table?
O A arrive in Asia; arrive in Australia and Pacific islands
B. arrive in Asia, arrive in the Americas
o
C. arrive in Australia and Pacific islands, arrive in the Americas
D. arrive in Australia and Pacific islands; arrive in Asia

two jet streams that directly affect the formation of weather in the continental part are a polar jet and a subtropical jet. they are responsible for the transportation of weather systems, which directly affect people. the polar front is the boundary between cold air from the north pole and warmer equatorial air. both the polar jet and the subtropical jet blow from the west to the east, and follow the boundary between cold and warm air.

the strongest jet streams are polar jets, while subtropical jets are somewhat weaker.

the right answer is c. the polar jet stream is generaly stronger than the subtropical jet stream.