You have data for many years on the average price of a barrel of oil and the average retail price of a gallon of unleaded regular gasoline. If you want to see how well the price of oil predicts the price of gas, then you should make a scatterplot with ___________ as the explanatory variable.

a. The price of oil

b. The price of gas

c. The year

d. Either oil price or gas price

e. Time

Select the best answer.