Two Zener diodes ($$A$$ and $$B$$) having breakdown voltages of $$6\,\text{V}$$ and $$4\,\text{V}$$ respectively, are connected as shown in the circuit below. The output voltage $$V_0$$ variation with input voltage linearly increasing with time, is given by ($$V_{input} = 0V$$ at $$t = 0$$):

A

B

C

E