Suppose an individual consumes pizza and cola. To reach consumer equilibrium, the individual must consume pizza and cola so that the a. price paid for the two goods is the same. b. marginal utility of the two goods is equal. c. ratio of marginal utility to price is the same for both goods. d. ratio of the marginal utility of cola to the marginal utility of pizza is 1

Statement (a) says that the price paid for both pizza and cola must be the same. This means the individual must spend the same amount of money on both products. However, it does not consider the utility the consumer gains from consuming these goods. So, statement (a) does not provide a proper condition for consumer equilibrium.

Statement (b) says that marginal utility of the two goods must be equal. Marginal utility is the additional satisfaction an individual gains from consuming an additional unit of a good. The consumer equilibrium condition should maximize the satisfaction from consuming a good given a fixed budget. If the marginal utility of the two goods is equal, the consumer could still gain more satisfaction by reallocating their budget between the goods. Hence, statement (b) does not provide a proper condition for consumer equilibrium.

Statement (c) says that the ratio of marginal utility to price is the same for both goods. This means that the consumer is getting the same satisfaction per dollar spent on both goods. In this case, the consumer is maximizing their satisfaction from consuming both goods given their budget constraint. Therefore, statement (c) provides a proper condition for consumer equilibrium: \(\frac{MU_{pizza}}{P_{pizza}} = \frac{MU_{cola}}{P_{cola}}\)

Statement (d) says that the ratio of the marginal utility of cola to the marginal utility of pizza is 1. This means that the marginal utility of cola is equal to the marginal utility of pizza, which is similar to statement (b). As we have already discussed, equal marginal utilities for both goods do not guarantee consumer equilibrium as it does not consider the constraint of budget and the prices of the goods. So, statement (d) does not provide a proper condition for consumer equilibrium. In conclusion, consumer equilibrium is reached when the ratio of marginal utility to price is the same for both goods, which is statement (c). The correct condition for consumer equilibrium is: \(\frac{MU_{pizza}}{P_{pizza}} = \frac{MU_{cola}}{P_{cola}}\)