In a control system with unity gain feedback, the plant has the transfer function P(s) = 3/s. Assuming that a controller of the form C(s) = K/(s + p) is used, where K is a positive constant, the value of p for which the root-locus of the closed-loop system passes through the points -3$\pm$j3$\sqrt{3}$ where j = $\sqrt{-1}$, is
- 3
- 3$\sqrt{3}$
- 6
- 9