What's the correct formula to calculate operating free cash flow (OFCF, also called unlevered firm free cash flow) based on Net Income (NI) for a levered firm? Note that the OFCF should not include the benefit of interest tax shields.

Select one:

a. OFCF = NI + Depr - CapEx - DeltaNOWC

b. OFCF = NI + Depr - CapEx - DeltaNOWC + IntExp*tc

c. OFCF = NI + Depr - CapEx - DeltaNOWC + IntExp*(1-tc)

d. OFCF = NI + Depr - CapEx - DeltaNOWC + IntExp

e. OFCF = NI + Depr - CapEx - DeltaNOWC - IntExp*tc