If E Is the Real Exchange Rate, E' Is the Nominal

If e is the real exchange rate, e' is the nominal exchange rate, P is the domestic price level, and Pf is the foreign price level, then

A) e' ( = e(P/Pf) .
B) e = e' (P/Pf) .
C) e = e' (Pf/P) .
D) e = Pf/e' (P.