Choice "D" is correct. Cost (Push) inflation is inflation caused by a shift left in aggregate supply. An increase in input costs, such as a sharp increase in the price of oil, will cause the short-run aggregate supply curve to shift left and thus increase the aggregate price level causing inflation.
Choice "c" is incorrect. Demand (Pull) inflation is inflation caused by a shift right in aggregate demand.
Choice "b" is incorrect. An increase in the price of oil causes the aggregate supply curve to shift, not the aggregate demand curve.
Choice "a" is incorrect. An increase in the price of oil will cause aggregate supply to decrease (shift left), not increase.