Aproblem encountered when the drug under study causes many different reactions. a type of study in which researchers examine what happens to a group of people over time. when one variable causes an observed result. when two variables are related to one another in a predictable manner. when the effect of one variable hides the effect of the other variable.

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.

the answer is d. amendments.

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