During an experiment with a metre bridge, the galvanometer shows a null point when the jockey is pressed at `40.0 cm` using a standard resistance of `90 Omega`, as shown in the figure. The least count of the scale used in the metre bridge is 1mm. The unknown resistance is
A. `60 pm 0.15 Omega`
B. `135 pm 0.56 Omega`
C. `60 pm 0.25 Omega`
D. `135 pm 0.23 Omega`