In the circuit, switch '$S$' is in the closed position for a very long time. If the switch is opened at time $t = 0$, then in $i_{L} (t)$ amperes, for $t\geq0$ is
1. $8e^{-10t}$
2. $10$
3. $8+2e^{-10t}$
4. $10\left ( 1-e^{-2t} \right )$