The correct option is C VR2 at t=0 and V(R1+R2)R1R2 at t=∞
After closing key K, at t=0, the coil offers infinite resistance.
⇒ Effective resistance is R2
⇒ Current, I=VR2
At t=∞, the coil offers zero resistance.
⇒ Effective resistance is (R1R2R1+R2)
⇒ Current, I′=VR1R2(R1+R2)=V(R1+R2)R1R2