Explanation: Dirty or salt-encrusted insulation introduces undesirable conductive paths across the insulator's surface. These contaminants significantly lower the effective resistance of the insulation, especially in the presence of moisture. **Increased corona discharge:** The compromised insulation and surface contaminants reduce the dielectric strength, making it easier for high RF voltages to ionize the surrounding air. This results in visible corona discharge, which is a phenomenon where energy is lost as light, heat, and sound, rather than being radiated. **Erratic readings of antenna current:** The conductive paths can shunt some of the RF current away from the antenna's radiating elements. The conductivity of these paths can fluctuate with environmental factors like humidity, temperature, or the level of contamination, leading to unstable and inaccurate current readings. Corona discharge itself can also cause non-linear effects that contribute to erratic measurements. **Decreased radiation power:** Both the parasitic current leakage through the dirty/salt-encrusted insulation and the energy lost due to corona discharge represent a direct conversion of RF energy into heat and other non-radiating forms. This reduces the overall efficiency of the antenna system, meaning less power is actually radiated as electromagnetic waves. Because all three listed effects are direct consequences of compromised insulation, "All of the above" is the correct answer.