系统的开环传函为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/4c0fd44e4fd34ba5abebcf5cf4075e5b.png" />，根轨迹和虚轴的交点及相应的根轨迹增益为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/1a01ea0a12204b8395a0b5b77f6dff14.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5973aa4feb8b449e936c4db36ba0f235.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/3212607aceba42119e02c092ee59c4c9.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5e06d749351c40758f2d90bd5503ac41.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/646b41ca995f4f9883b1d2c4a17a1b4c.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/f268e2b90534408293cc995f99bf8907.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/212d583db0b74c5a84acfc955c422863.png" />，<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/5e06d749351c40758f2d90bd5503ac41.png" />