The R.L, of the point A which is on the floor is 100 m and back sight reading on A is 2.455 m. If the foresight reading on the point B which is on the ceiling is 2.745 m, the R.L. of point B will be_______________?
A. 94.80 m
B. 99.71 m
C. 100.29 m
D. 105.20 m