A process with transfer function, $G_{p}=\frac{2}{s-1}$ is to be controlled by a feedback proportional controller with a gain $K_{c}$. If the transfer functions of all other elements in the control loop are unity, the which $ONE$ of the following conditions produces a stable closed loop response ?

1. $K_{c}=0.25$
2. $0<K_{c}<0.25$
3. $0.25<K_{c}<0.5$
4. $K_{c}>0.5$