Two D flip-flops are connected as a synchronous counter that goes through the following Q_B Q_A sequence $$00 \to 11 \to 01 \to 10 \to 00 \to ......$$

The output of a 3-stage Johnson (twisted-ring) counter is fed to a digital-to-analog (D/A) converter as shown in the figure below. Assume all the states of the counter to be unset initially. The waveform which represents the D/A converter output V_o is

What are the counting states (Q₁, Q₂) for the counter shown in the figure below?

For each of the positive edge-triggered J-K flip flop used in the following future, the propagation delay is $$\Delta $$T

Which of the following waveforms correctly represents the output at Q₁?