S Curve re-baseline retrospective comparison

Dear All,

I have re-baselined a percentage complete (earned Man-hour value / budgeted Manhour value)  v/s. Time S - Curve at 75% project completion.

Subsequently I have been asked to determine Retrospectively , what was the earned value % when the project was at 50% completion. In such a case should the earned value % be

a) Actual earned value % (say 45% at 50% completion) because the rebaselining had been done AFTER 50% milestone had been completed OR

b) Earned Value % shall be equal to 50% at 50% completion because the S - Curve has been re-baselined.

I am aware that Rebaseline affects the forecast / 'To go' part of the S - Curve with the Actual % = Planned % ON the date of the rebaseline. But what about the PAST Actual percentages , do they also become Actual % = Planned % on re-baselining ?

Kindly let me have your opinion.

SH