How is the transient current in a loss-free R-L-C circuit?

The correct answer is option 4.

Concept: 

The RLC circuit means the series or parallel connection of the resistance(R), inductor(L), and capacitor(C).

A series circuit is given below.

Since it is mentioned that the circuit is a loss-free circuit the current will behave similarly to that of an LC series circuit i.e. an undamped sinusoidal waveform will be observed.

In a loss-free circuit, the energy keeps shifting between L and C.

 Important PointsIf the case would have been of loss-making RLC series circuit then the current would have a damped sinusoidal equation.