Christina Romer's Criticism of the Belief That Business Cycles Had

Christina Romer's criticism of the belief that business cycles had moderated since World War II depended on the fact that

A) estimates of the timing of business cycles since World War II had been inaccurate.
B) misuse of historical data had caused economists to understate the size of cyclical fluctuations in the post-World War II era.
C) economists had ignored the roles of the government and international trade in mitigating economic fluctuations prior to World War II.
D) economists had left out important components of GDP, such as wholesale and retail distribution, transportation, and services, in their pre-World War II estimates.