If People Have Rational Expectations,but They Are Not Always Correct

Multiple Choice

If people have rational expectations,but they are not always correct in their expectations,the expectation of a lower inflation rate will cause:

A) the short-run Phillips curve to become vertical.
B) the short-run Phillips curve to shift leftward.
C) a movement down along a short-run Phillips curve.
D) the short-run Phillips curve to shift rightward.