The driving point impedance $Z(s)$ for the circuit shown below is
1. $\dfrac{s^4+3s^2+1}{s^3+2s} \\$
2. $\dfrac{s^4+2s^2+1}{s^2+2} \\$
3. $\dfrac{s^2+1}{s^4+s^2+1} \\$
4. $\dfrac{s^3+1}{s^4+s^2+1}$