V0=Vi when no current flow through 1kΩ for negative values of Vi i from D1=0 (always) i from D2=0 upto 3V So from 0 to - 3V, Vi=V0 from - 3 to - 4 V, V0=−3V For positive values of Vi i from D1=0 upto 1V i from D2=0 (always) Hence 0 to 1V, Vi=V0 1 to 4 V, V0 = 1 volt Correct graph is (A)