What is the key idea in the aggregate expenditure macroeconomic model? The key idea in the aggregate expenditure model is that A. in any particular year, the level of potential real GDP is determined by the level of aggregate expenditure. B. long run economic growth is determined by the level of aggregate expenditure. C. in any particular year, the level of GDP is determined mainly by the level of aggregate expenditure. D. in any particular year, the inflation rate is determined only by the level of aggregate expenditure.