The output of a standard second-order system for a unit step input is given as $y(t) = 1-\dfrac{2}{\sqrt{3}}e^{-t}\cos \left(\sqrt{3t}-\dfrac{\pi}{6}\right)$. The transfer function of the system is
- $\dfrac{2}{(s+2)(s+\sqrt{3})}$
- $\dfrac{1}{s^{2}+2s+1}$
- $\dfrac{3}{s^{2}+2s+3}$
- $\dfrac{3}{s^{2}+2s+4}$