The percent of a population living in an urban area is called the: A. rate of urban growth.
B. counter urbanization,
C. urban hierarchy.
D. urbanization rate.

C-urban hierarchy

Explanation:Urban hierarchy is the rank based on the size of the population residing within an urban area.

Counter urbanization is a social process in which people move from urban areas to rural areas.

Urbanization rate is the increase in the proportion of urban population over some time.

That is why the answer is C.

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.