ANS:A - decay to zero at the end of the pulse

It is clear the time constant=L/R=2 microseconds and Time period=1/f=10micro seconds as the time period is 5 times of time constant say 5 torr.

So in this time period, the inductor is fully charged when pulse ends the inductor is fully charged and the voltage across inductor will be zero because inductor is a device which stores energy in terms of current. At the start the inductor behaves like open and when fully charged it behaves like short so that the voltage will be zero.

I hope you will be understand.