What is the range of ‘K’ for the which the unity feedback closed loop system with open loop gain \(G\left( s \right) = \frac{K}{{{s^2}\left( {s + a} \right)}}\) will be unstable?

• A. -a < K < a
• B. K > 0
• C. K = 0
• D. -∞ < K < ∞