In the following examples, identify the exogenous (or independent) variable and the endogenous (or dependent) variable.
a. The amount of rainfall on the Canadian prairies determines the amount of wheat produced in Canada.
b. When the world price of coffee increases, there is a change in the price of your cup of coffee at Tim Hortons.
c. If student loans were no longer available, there would be fewer students attending university.
d. An increase in the tax on gasoline leads people to drive more fuel-efficient vehicles.