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Common Data for Questions 53 and 54:

The Nyquist plot of a stable transfer function $G(s)$ is shown in the figure. We are interested in the stability of the closed loop system in the feedback configuration shown.

The gain and phase margins of $G(s)$ for closed loop stability are

1. $6 \mathrm{~dB}$ and $180^{\circ}$
2. $3 \mathrm{~dB}$ and $180^{\circ}$
3. $6 \mathrm{~dB}$ and $90^{\circ}$
4. $3 \mathrm{~dB}$ and $90^{\circ}$