Question: For each of the following situations, which is the explanatory variable and which is the response variable?
a. The two variables are whether or not someone smoked and whether or not the person developed Alzheimer's disease.
b. The two variables are whether or not somebody voted in the last election and the person's political party (Democrat, Republican, Independent, or Other).
c. The two variables are income level and whether or not the person has ever been subjected to a tax audit.