If initially the money supply is​ $1 trillion, velocity is​ 5, the price level is​ 1, and real GDP is​ $5 trillion, an increase in the money supply to​ $2 trillion A. increases real GDP to​ $10 trillion. B. causes velocity to fall to 2.5. C. increases the price level to 2. D. increases the price level to 2 and velocity to 10.