The correct answer is: D. Different combination of two goods among which the consumer is indifferent.
An indifference curve is a graph showing combinations of goods that provide the same level of satisfaction to a consumer. It is a downward-sloping curve because consumers are willing to give up some of one good in order to get more of another good, as long as they are compensated with enough of the other good to maintain the same level of satisfaction.
Option A is incorrect because an indifference curve does not show affordable combinations of goods. It shows combinations of goods that provide the same level of satisfaction.
Option B is incorrect because an indifference curve does not show the relative price of one good to another. It shows combinations of goods that provide the same level of satisfaction.
Option C is incorrect because an indifference curve does not show consumption possibilities that a consumer faces at different price and income. It shows combinations of goods that provide the same level of satisfaction.