Which of the following features is not associated with Nichols chart?

• A. (0 dB, -180°) point on Nichols chart represent critical Point (-1, 0)
• B. It is symmetric about -180°
• C. M loci are centred about (0 dB, -180°) point
• D. The frequency at intersection of G(j?) locus and M = +3 dB locus gives bandwidth of closed loop system