Explanation: An antenna's resonant frequency occurs when its inductive reactance ($X_L$) equals its capacitive reactance ($X_C$). At resonance, these reactances cancel, leaving a purely resistive impedance. Adding an inductor in series with an antenna increases the total inductive reactance ($X_L$) of the circuit. To restore the balance for resonance ($X_L = X_C$), the capacitive reactance ($X_C$) must also increase to match the new, higher $X_L$. Since capacitive reactance ($X_C = 1 / (2\pi fC)$) is inversely proportional to frequency, an increase in $X_C$ requires a *decrease* in frequency. Therefore, adding an inductor in series makes the antenna electrically "longer" and lowers its resonant frequency. Options B, C, and D are incorrect. Adding inductance does not increase the resonant frequency (that would require adding capacitance or shortening the antenna). Neutralization and equalization are terms related to amplifier stability or frequency response shaping, respectively, not the direct effect of adding series inductance on antenna resonance.