Notes上的一道题，答案选C，我想知道D为什么不对？

For a demand-pull effect or a cost-push effect to cause inflation:
A. the AS curve has to shift in response to a shift of the AD curve.
B. the AD curve has to shift in response to a shift of the AS curve.
C. the cause of the shift in AD or AS must be repeated or sustained.
D. economic equilibrium must be re-established at a higher price level.

楼主这道题问得很好 我也做错了 选的D

看一下NOTES底167-168页的细节内容。因为inflation的一个特点在于price的上涨是persist的，168页第三段开头那句话，以及167页倒数第二段，Demand-pull inflation would persist until the central bank reduced the growth rate of the money supply....因此，既然inflation是不断的一个螺旋过程，那么就没有说停下来，reestablish在某一个点。

我想这道题大概是这个意思吧。