New Keynesian economists have examined whether real-world prices are, in fact, sticky. In one study of 38 magazines, Stephen Cecchetti found

a. that price rigidity was nonexistent with respect to magazines at newsstands.
b. considerable rigidity with respect to the newsstand prices of magazines.
c. that most of the 38 magazines in the study had price changes at least once a year.
d. that the Readers Digest price was changed 15 times between 1950 and 1980.

B