When a parallel coil-capacitor combination is supplied with AC of different frequencies, there will be one frequency where the impedance will be highest. This is the:

In a parallel LC circuit (a coil and a capacitor connected in parallel), the overall impedance changes as the frequency of the applied AC changes. At the specific frequency where the inductive reactance exactly equals the capacitive reactance, the circuit reaches resonance. At this resonant frequency, the parallel circuit exhibits its highest possible impedance to the AC source, effectively blocking the source current. Frequencies above or below this point will encounter a lower impedance and thus draw more current from the source. Terms like "inductive frequency" or "reactive frequency" are fabricated distractors. The unique point of maximum impedance in a parallel circuit is always defined as its resonant frequency.