Identify whether the following will represent a shift in the Phillips curve or a movement along the Phillips curve. Illustrate with a graph.

a. Consumer confidence increases unexpectedly and causes the output gap to become more positive.

b. Inflation last year was far greater than even the best forecaster expected even though the output gap was zero.

c. A devastating late-spring freeze destroys crops across the eastern United States, which causes the output gap to become more negative.