In case of reduction of levels by the height of instrument method,

• A. B.S. - F.S. = difference in R.L.S of the first station and last station
• B. (R.L. + I + F.S.) - first R.L = (H.I. + No. of R.L.s.)
• C. both (a) and (b) above
• D. neither (a) nor (b).