How does an increase in the price level affect the quantity of real GDP supplied in the long​ run? A. In the long​ run, an increase in the price level increases​ inflation, which will decrease real GDP. B. Changes in the price level do not affect the level of GDP in the long run. C. In the long​ run, an increase in the price level decreases​ inflation, which will decrease real GDP. D. In the long​ run, an increase in the price level will increase real GDP.