Which of the following statements is true when the consumer is in util

Which of the following statements is true when the consumer is in utility-maximizing equilibrium?

A) The number of units of each good purchased is equal.
B) The prices of the goods in question must be equal.
C) The total benefits the consumer receives from every good consumed must be the same for all goods.
D) The rate at which the consumer is willing to trade one good for another is equal to the ratio of their market prices.

ANSWER

D