The output of a standard second – order systems for a unit step input is given as\({\rm{y}}\left( {\rm{t}} \right) = 1 - \frac{2}{{\sqrt 3 }}{{\rm{e}}^{ - {\rm{t}}}}\cos \left( {\sqrt {3{\rm{t}}} - \frac{{\rm{\pi }}}{6}} \right)\)The transfer function is the system is

• A. \(\frac{2}{{\left( {{\rm{s}} + 2} \right)\left( {{\rm{s}} + \sqrt 3 } \right)}}\)
• B. \(\frac{1}{{\left( {{{\rm{s}}^2} + 2{\rm{s}} + 1} \right)}}\)
• C. \(\frac{3}{{{{\rm{s}}^2} + 2{\rm{s}} + 3}}\)
• D. \(\frac{4}{{{{\rm{s}}^2} + 2{\rm{s}} + 4}}\)