Why Is the Expected Inflation Rate Rather Than the Current

Why is the expected inflation rate rather than the current inflation rate typically used in analysis of the Fisher effect?

A) The Fisher effect is an estimate, so an estimated inflation rate is more appropriate than an actual inflation rate.
B) The expected inflation rate is what impacts the current real interest rate because the current inflation rate impacts that past.
C) The Fisher effect deals with the future and does not explain the present situation.
D) Interest rates impact borrowing and saving, which are activities that have connections to the future.