Which of the following statements is correct?

Select one:

a. New Keynesians believe that the aggregate supply curve is vertical in the short run but not in the long run.

b. Both new classicals and new Keynesians believe that the aggregate supply curve is vertical in the long run.

c. New Keynesians believe that the aggregate supply curve slopes upward in the long run.

d. New classicals believe that the aggregate supply curve is a vertical line in both the short run and the long run.