Resistance of a conductivity cell filled with $0.1 \ mol \ L^{-1}$ $NaCl$ is $100 \ \Omega$. If the resistance of the same cell when filled with $0.02 \ mol \ L^{-1}$ $NaCl$ solution is $258 \ \Omega$,the conductivity of $0.02 \ mol \ L^{-1}$ $NaCl$ solution is (Conductivity of $0.1 \ mol \ L^{-1}$ $NaCl$ is $1.29 \ S \ m^{-1}$) (in $S \ m^{-1}$)

• A
  $1.0$
• B
  $0.2$
• C
  $2.0$
• D
  $0.5$