Which of the Following Is True

Multiple Choice

Which of the following is true?

A) The Phillips curve trade-off holds in the long run but not necessarily in the short run because of randomness in markets.
B) A.W. Phillips' original work related changes in unemployment and changes in prices; later economists demonstrated that there was also a trade-off between changes in prices and changes in unemployment.
C) In the short run, there is a trade-off between inflation and unemployment even if the change in aggregate demand is expected.
D) Although a trade-off exists in the short run, in the long run, the Phillips curve is vertical.