For the following list, identify the best choice for an independent and a dependent variable, taking into account the type of case for which data were collected. Explain your choice. Remember that, in some cases, either variable could be the IV or the DV.

a) Individuals: college grade point average and family income

b) Countries: infant mortality rate and number of doctors per capita

c) Individuals: attitude on the death penalty and attitude on abortion

d) States or provinces: high school dropout rate and crime rate