Which of the following describes a type of antenna loading?

Antenna loading refers to the practice of inserting an electrical component, typically a loading coil (inductor), into an antenna's radiating element. This artificially increases the electrical length of the antenna, allowing it to become resonant at a lower frequency than its physical length would normally permit. This is extremely common in mobile HF antennas where full-sized elements are impractical. The other options misuse the word 'loading.' Inserting a resistor would simply dissipate valuable transmit power as heat, not make the antenna resonant. Mechanical spring bases or wind-resistant strengthening represent physical, structural adjustments, not electrical 'loading.'