A buyer has $20 to spend on rice and beans. Rice costs $2 and beans cost $3 per pound. The buyer is buying the combination of 4 pounds of rice and 4 pounds of beans. At this combination, her marginal benefit from rice is $14 and her marginal benefit from beans is $18. This buyer should ________. a. buy less beans and more rice b. buy more rice and less beans c. buy more of both rice and beans d. not change his consumption