The open-loop transfer function of unity feedback (negative feedback) system is \(G\left( s \right) = \frac{K}{{s\left( {s + 2} \right)\left( {{s^2} + 2s + 2} \right)}}\). Then the closed-loop transfer function for k = 1 is
1
\(\frac{1}{{{{\left( {s + 1} \right)}^3}}}\)
2
\(\frac{1}{{{{\left( {s + 1} \right)}^4}}}\)
3
\(\frac{1}{{{{\left( {s - 1} \right)}^2}\left( {{s^2} + 2s + 1} \right)}}\)
4
\(\frac{1}{{{{\left( {{s^2} + 2s - 1} \right)}^2}}}\)