Weaken Questions - #18

Great question. The purchase price would remain the same, even if the quantity increased. It is still (say) $4/gallon even if they buy twice as much. Does that help?

I chose D too but now I see why it's wrong. "amount of gasoline purchased" is irrelevant to the "price of oil" and the "consumer purchase price of gas." Stimulus is an example of a correlation. Am I correct?