Final answer:
A budget constraint (or budget line) shows the possible combinations of affordable goods given a consumer's limited income.
Step-by-step explanation:
A budget constraint (or budget line) shows the possible combinations of two goods that are affordable given a consumer's limited income. It represents the trade-offs a consumer must make in order to purchase different quantities of two goods, given their prices and the consumer's income. The budget constraint is usually represented graphically as a straight line that shows all the affordable combinations of the two goods.