Which of the Following Will Change the Slopes of Your

Which of the following will change the slopes of your indifference curves between gasoline and movie rentals?

A) a change in your preferences for either of the two goods
B) only a change in the price of either of the two goods
C) only a change in your income
D) Both a change in the price of either good and a change in income will change the slopes of your indifference curves.