In the meter bridge experiment, the length AB of the wire is 1 m. The resistors $X$ and $Y$ have values $5 \Omega$ and $2 \Omega$ respectively. When a shunt resistance $S$ is connected to $X$, the balancing point is found to be $0.625\;m$ from A. Then, the resistance of the shunt is

Question

$ (a) \; 5\; \Omega \\(b)\; 10\;\Omega\\(c)\; 7.5\; \Omega \\(d) \;12.5 \; \Omega $