One thing that distinguishes normative economic principles from positive economic principles is that:

A.normative principles are pessimistic and positive principles are optimistic.

B.normative principles reflect social norms, and positive principles reflect universal truths.

C.normative principles tell us how people will behave, and positive principles tell us how people should behave.

D.normative principles tell us how people should behave, and positive principles tell us how people will behave.

正确答案：normative principles tell us how people should behave, and positive principles tell us how people will behave.