Katie finds that the marginal utility from a compact disc is 30 and the marginal utility from a pizza is 10. The price of a compact disc is $15 and the price of a pizza is $10. In order to increase her utility, Katie should
选项：

A: consume more compact discs and fewer pizzas.
B: consume fewer compact discs and more pizzas.
C: not change her consumption of pizza and compact discs.
D: consume fewer compact discs and fewer pizzas.