On doping germanium with donor atoms of density $10^{17} cm^{-3}$ its conductivity in mho/cm will be [Given : $μ_e = 3800cm^2/ V−s$ and $n_i=2.5×10^{13}cm^{−13}$]

30.4 60.8 91.2 121.6

60.8

Conductivity $σ=n_ieμ_e=10^{17}×(1.6×10^{-19})×3800=60.8mho/cm$