The Scarcity Principle tells us _, and the Cost-Benefit Principle tells us _.

题目：The Scarcity Principle tells us _, and the Cost-Benefit Principle tells us _.

The Scarcity Principle tells us _, and the Cost-Benefit Principle tells us _.

A.how to make good choices; that choices involve costs and benefits

B.that good choices eliminate scarcity; how to make good choices

C.how to make choices; that choices must be made

D.that choices must be made; how to make good choices


正确答案：that choices must be made; how to make good choices