Which transmission line type is likely to produce more reactive power?

The option that produces more reactive power among the choices provided is typically associated with overhead lines rather than underground cables. Underground cables are generally designed to have lower capacitance compared to overhead lines, which makes them less likely to generate reactive power.

In contrast, lightly loaded short overhead lines can exhibit significant reactive power characteristics. When these lines are unloaded or lightly loaded, they may produce reactive power due to the inherent capacitance associated with overhead lines, which can lead to voltage rise and reactive output.

Loaded tie-lines can also produce reactive power because they generally connect different systems or grids, allowing for the transfer of both real and reactive power under load conditions. However, the extent of reactive power they produce depends significantly on the loading conditions and the configuration of the system.

Radial lines with capacitor banks in service are designed to enhance voltage stability and manage reactive power flow, thereby contributing to reactive power production. However, the presence of capacitor banks usually serves to supply reactive power rather than producing it inherently.

Overall, while underground cables have different operational characteristics, overhead lines, especially when lightly loaded, are more efficient at generating reactive power, which makes this option a more compelling choice when considering the dynamics of power systems.