Correct Answer - C
The percentage error in R can be minimised by adjusting the balance point near the middle of the bridge, i.e., when `I_(1)` in close to 50 cm. this requires a suitable choice of S.
Since, `(R)/(S)=(Rl_(1))/(R(100-l_(1)))=(l_(1))/(100-l_(1))`
Since here `R:S::2.9:97.1` imply that the S is nearly 33 times to that of R. in orded to make this ratio 1:1, it is neccesary to reduce the value of S nearly `(1)/(33)` times i.e., nearly `3Omega`.