When moving between two points on an indifference curve, why is the marginal utility of consuming more of one good equal to the marginal utility lost by consuming less of the other good?
a. Because each point on the indifference curve represents that same level of utility for any combination of the two goods
b. Because a person can get more of one good if they give up some of the other good.
c. Because an individual's budget constraint will change over time.
d. Because of the law of substitution over the long run.