Explanation: In a series R-L-C circuit, the total opposition to current flow is called impedance (Z). Impedance is a combination of resistance (R) and the net reactance, which is the difference between inductive reactance (XL) and capacitive reactance (XC). These reactances have opposing effects. At resonance, the inductive reactance (XL) exactly cancels out the capacitive reactance (XC), meaning XL - XC = 0. This causes the total impedance (Z) of the circuit to become equal to just the resistance (R). Since resistance is the inherent minimum opposition to current in the circuit, the impedance at resonance is at its *minimum* possible value. According to Ohm's Law (I = V/Z), for a given voltage (V), a minimum impedance (Z) results in a *maximum* current (I) flow. Therefore, at resonance in a series R-L-C circuit, the current flow is maximum. Option B is incorrect because minimum current occurs in a *parallel* resonant circuit, where impedance is maximum. Options C and D are incorrect as the current in an AC RLC circuit is alternating current, not DC, and it is not zero.