If inflation is mainly and everywhere a monetary phenomenon, why can we observe inflation correlated with lower unemployment, as in the case of Mr. Phillips's doctoral dissertation covering over 100 years in England? (Venezuela has hyperinflation, and unemployment is at a record high level.) a) An increase in M leads to a higher Y. b) An increase in Y leads to a lower U. c) An increase in M higher than Y leads to unexpected higher inflation. d) All of the above