The correct option of this question will be (b)
Solution —
$G=100 \Omega, I_{g}=10^{-5} \mathrm{~A}, I=1 \mathrm{~A}$ To convert the galvanometer into an ammeter, we should connect a resistance $S$ in parallel to it.
$\therefore I_{g} \times G=\left(I-I_{g}\right) \times S $
$S=\left(\frac{I_{g}}{I-I_{g}}\right) \times$ $G=\frac{10^{-5}}{1-10^{-5}} \times 100$
or $S=\frac{10^{-3}}{1-0.00001}=10^{-3} Ω$