A downward sloping marginal product of labor curve demonstrates the law of diminishing marginal returns

"Higher ethanol production definitely and directly raises the price of corn," said USDA economist Ephraim Leibtag. In the long run in the corn market, what is TRUE if the production of ethanol increases?

A) Existing corn farmers will exit the market and decrease the market price. B) New corn farmers will enter the market and increase the market price. C) Existing corn farmers will exit the market and increase the market price. D) New corn farmers will enter the market and decrease the market price.

When the aggregate demand curve shifts to the left against a vertical aggregate supply curve, the price level should __________ unless, as __________ argue, prices may have rigidities

A) fall; Keynesians B) fall; Monetarists C) rise; Keynesians D) rise; Monetarists