Why Impedance, symbol Z, measured in ohms, is the total opposition a circuit presents to alternating current. It combines resistance (opposition that dissipates power) with reactance from capacitors and inductors (opposition that depends on frequency), so Z is the AC counterpart of plain DC resistance.
Watch out The inverse of resistance is conductance, measured in siemens, and the inverse of reactance is susceptance; neither describes impedance, which is a sum of resistance and reactance effects, not an inverse.
Z = ohms of opposition to AC. Resistance + reactance = impedance.
IMPEDE is sitting right inside impedance, and to impede is to oppose. Pick the choice that says opposition.