All transmission line sections shown in the figure is have a characteristic impedance $\text{R}_{0}+\text{j}_{0}$. The input impedance $\text{Z}_{\text {in}}$ equals
- $\frac{2}{3} \text{R}_{0}$
- $\mathrm{R}_{0}$
- $\frac{3}{2} \text{R}_{0}$
- $2 \mathrm{R}_{\mathrm{0}}$