The sensitivity of a galvanometer is $60$ divisions /Amp. When a shunt is used, its sensitivity become 10 divisions/Amp. If the galvanometer is of resistance $20 \Omega$, the value of shunt used is :

Question

$$\begin {array} {1 1} (a)\;4 \Omega & \quad (b)\;5 \Omega \\ (c)\;20 \Omega  & \quad (d)\;2 \Omega \end {array}$$