Correct Answer - D
From the given transfer characteristics of a base biased common emitter transistor
(i) When `V_i=1 V`, which is in between 0.6 V to 2 V the transistor circuit is in active state and is used as an amplifier.
(ii) When `V_i = 0.5 V` there is no collector current. The transistor is in cut off state. The transistor circuit can be used as a switch turned off
(iii) When `V_i = 2.5 V`, the collector current becomes maximum and transistor is in saturation state and can be used as switch turned on state. So option (a) (b) and (c) are correct