An ice cube of dimensions $60\,cm \times 50\,cm \times 20\,cm$ is placed in an insulation box of wall thickness $1\,cm$. The box keeping the ice cube at $0^{\circ}C$ temperature is brought to a room of temperature $40^{\circ}C$. The rate of melting of ice is approximately. (Latent heat of fusion of ice is $3.4 \times 10^{5}\,J\,kg^{-1}$ and thermal conductivity of insulation wall is $0.05\,W\,m^{-1\circ}C^{-1}$)

• A
  $61 \times 10^{-1}\,kg\,s^{-1}$
• B
  $61 \times 10^{-5}\,kg\,s^{-1}$
• C
  $208\,kg\,s^{-1}$
• D
  $30 \times 10^{-5}\,kg\,s^{-1}$