The Nyquist plot for the open-loop transfer fucntion G(s)

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The Nyquist plot for the open-loop transfer fucntion G(s) of a unity negative feedback system is shown in the figure. If G(s) has no pole in the right-half of s-plane, the number of roots of the system characteristic equation in the right-half of s-plane is

1. 0
2. 1
3. 2
4. 3

Correct Option: A

P = 0
N = 0, since encirclement is zero,
As, P = N + Z.
∴ Z = 0.