At $25^{\circ }\text{C}$, the molar conductance of a $0.1\text{M}$ aqueous solution of ammonium hydroxide is $9.54{\Omega }^{-1}{\text{cm}}^2{\text{mol}}^{-1}$ and at infinite dilution its molar conductance is $238{\Omega }^{-1}{\text{cm}}^2{\text{mol}}^{-1}$. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is:

1. A
   $2.080\%$
2. B
   $20.800\%$
3. C
   $4.008\%$
4. D
   $40.800\%$