The correct answer is A. Minimum.
In a series resonant circuit, the inductive reactance and capacitive reactance are equal in magnitude and opposite in sign, so they cancel each other out. This leaves only the resistance in the circuit, which is the only component that contributes to the impedance. Therefore, the impedance of the circuit is at its minimum value at resonance.
Option B is incorrect because the impedance of a series resonant circuit is not at its maximum value at resonance. In fact, the impedance is at its minimum value at resonance.
Option C is incorrect because the impedance of a series resonant circuit is not zero at resonance. The impedance is at its minimum value at resonance, but it is not zero.
Option D is incorrect because the impedance of a series resonant circuit is not none of the above. The impedance of a series resonant circuit is at its minimum value at resonance.