Suppose Lisa, who is a freelance publicist for several alternative rock labels, earns $50,000 annually. To maximize her total utility, she will spend the income in such a way that

a. the marginal utility she derives from every good she buys is zero.

b. the marginal-utility-to-price ratio for each of the goods she buys is zero.

c. the marginal-utility-to-price ratio for each of the goods she buys is at its maximum.

d. the marginal-utility-to-price ratio for each of the goods she buys is at its minimum.

e. the marginal-utility-to-price ratio for each of the goods she buys is equal.