Correct Answer - D
In the branch containing `L` and `R^(2)`
`i=(E)/(R_(2))(1-e^(-(R_(2)t)/(L)))`
`(di)/(dt)=(E)/(R_(2))e^((-R_(2)t)/(L)).(R_(2))/(L)=(E)/(L)e^(-(R_(2)t)/(L))`
`V_(L)=L(di)/(dt)=Ee^(-(R_(2)t)/(L))=12e^(-(2xxt)/(400xx10^(-3))`
`=12e^(5t)V`