For each problem, select the best response.

(a) The Columbus Zoo conducts a study to determine whether a household's income can be used to predict the amount of money the household will give to the zoo's annual fund drive. The response variable in this study is

A. a household's income.
B. the amount of money a household gives to the zoo's annual fund drive.
C. all households in Columbus.
D. the Columbus Zoo.
E. None of the above.

(b) A researcher measures the correlation between two variables. This correlation tells us

A. whether a cause-and-effect relation exists between two variables.
B. whether there is a relation between two variables.
C. whether or not a scatterplot shows an interesting pattern.
D. the strength of a straight line relation between two variables.
E. None of the above.

(c) A researcher wishes to determine whether the rate of water flow (in liters per second) over an experimental soil bed can be used to predict the amount of soil washed away (in kilograms). In this study, the explanatory variable is the

A. amount of eroded soil.
B. depth of the soil bed.
C. size of the soil bed.
D. rate of water flow.
E. None of the above.