What is the marginal revenue of producing the fourth unit?

A country reported a nominal GDP of $85 billion in 2010 and $100 billion in 2009. It also reported a GDP deflator of 100 in 2010 and 105 in 2009. Between 2009 and 2010,

a. real output and the price level both rose. b. real output rose and the price level fell. c. real output fell and the price level rose. d. real output and the price level both fell.

There is $5,000,000 of currency in Econland, all held by banks as reserves. The public does not hold any currency. If the banks' desired reserve/deposit ratio is 0.25, then the money supply equals:

A. $20,000,000 B. $10,000,000 C. $6,250,000 D. $5,000,000