We reveal that the temperature dependence of the basal-plane normal-state electrical resistance of opti- mally doped YBa 2 Cu 3 O 7 −δsingle crystals can be with great accuracy approximated within the framework of the model of s-d electron-phonon scattering. This requires taking into account the fluctuation con- ductivity whose contribution exponentially increases with decreasing temperature and decreases with an increase of oxygen deficiency. Room-temperature annealing improves the sample and, thus, increases the superconducting transition temperature. The temperature of the 2D-3D crossover decreases during annealing.