问题如下：
Based on Real Business Cycle models, which of the following may lead to an economic contraction:
选项：
A.decreased money supply.
B.increased oil prices.
C.technology progress.
解释：
B is correct.
Based on Real Business Cycle models, external shock is the main reason that causes an economy to expand or contract. The increased oil prices will lead to an increase of overall prices level, which may finally result in an economic contraction.
考点： Real Business Cycle models
解析： Real Business Cycle models 认为经济的运行好坏和货币发行量并无关系，所以A选项错误。
Real Business Cycle models 认为经济周期的产生与外部冲击息息相关。石油这类重要工业原材料价格的上涨会带来经济的衰退，所以B选项正确。
技术的进步带来的是经济的繁荣而非衰退，所以C选项错误。
这题出的不严谨吧？石油价格下跌反而会引发通货紧缩，导致整体经济下行，无论对于俄罗斯、伊朗这种产油国，还是中国这种进口国都是一样的通过紧缩吧，当下不就是这样子吗？建议把选项改了
