Which of the following is a term for a variable that researchers do not control and that can affect the results of a study? Independent variable

Independent variable
A

Dependent variable

Dependent variable
B

Control variable

Control variable
C

Confounding variable

Confounding variable
D

Continuous variable

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Which of these is a disadvantage of hydrogen fuel cells? a. engines that use hydrogen fuel are more efficient than gasoline-powered engines. b. the only emission produced by hydrogen fuel cells is water. c. hydrogen fuel is continually available and useful for heating. d. hydrogen fuel is often purified in a process that emits lots of greenhouse gases.

The following table lists the birth rate, death rate, and net migration rate for egypt over the past 20 years. on a coordinate plane, plot the birth rate data and death rate data for egypt. clearly, show each data point and label each curve. be sure to label the graph and axes. save a copy of your graph. then answer the following questions: (14 points) a. what was the annual growth rate for egypt in 1990? what is the estimated annual growth rate in 2010? be sure to show your work for each answer. b. where does egypt most likely fall on the demographic transition model? explain your answer using data from the table. describe two changes within egyptian society that would likely be necessary for egypt to transition to the next stage in the model. c. assuming egypt’s current birth rate, death rate, and net migration rate trends continue, what will the country’s annual growth rate likely be in 2030? if this growth rate is accurate, what would its doubling time be in 2030?