The answer is D. Inferior good or services and necessities tend to have inelastic demand curves. Luxury goods or services tend to have elastic demand curves. As the price changes the quantity of cheap items sold does not respond to price because they are still needed or the change in price is irrelevant with respect to Income. When the price changes the quantity of expensive items sold responds to price aggressively because the change in price allows consumers to either increase the volume of their wants or cut the luxury items to budget because the demand of the expensive item have to take consumer income into account.