In a given circuit, current will be same at different frequencies if impedance is same. Current in the circuit will be maximum, if circuit is in resonance. Typical graph of current versus frequency of circuit is

Now, as resistance is independent of frequency. So, current will same when impedance at two frequencies is same. At lower frequency, capacitive reactance is more but at higher frequencies, inductive reactance dominates.

So,

For current to be same

Now, current is maximum at

Resonant frequency,

For given problem,

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