Ans. A

JFET is three terminal  amplifier(used to increase amplitude of signal). three terminals are Drain( to take out current), Source(Source from where current is given out ). Operation is quite simple of the JFET. When no voltage is applied to gate terminal and suppose we apply + voltage Between Drain and source, electron  flows  from drain to source in the channel (region which connects drain and source shown by white color area) which creates current. now if apply negative voltage at gate terminal it will produce depletion region between gate and channel(shown by red color) as we go on increasing the negative drain voltage it continuously increases width of depletion region at some point say pinch off point depletion regions are so closed that further increase in negative voltage has no effect on depletion region.at this point JFET possesses maximum current Idss which remain almost constant.

Region1 -->   Ohmic region  -->   Drain current increase with increase in Drain voltage at constant                                                              gate  voltage(1 st curve)
Region 2 -->  Saturation  -->        Drain current remain constant (Pinch off region)