Milton Friedman and Edmund Phelps Contributed Which Insight(s)to Phillips Curve

Multiple Choice

Milton Friedman and Edmund Phelps contributed which insight(s) to Phillips curve analysis?

A) that firms and workers care about real wages
B) that inflation and expected inflation influence each other
C) that,in the long run,the level of unemployment is independent of inflation
D) all of the above
E) none of the above