Derivative Controller

Q. A second order control system is designed using PD controller having $K_P,K_D$ as proportional and derivative constant respectively.

$\frac{G\left(s\right)}{1+G\left(s\right)H\left(s\right)}=\frac{4}{s^2+s+4}$

For maximum overshoot to be zero and $K_P=1$. Minimum value of $K_D$ is

1. 1.164
2. 3
3. 0.75
4. 4.65