P6 and P7 centers, which are responsible for semi-insulating properties of SiC, were shown to be neutral Si-C divacancies (VSi-VC)o having a triplet ground state. The EPR experiments that were performed at very low temperatures and in complete darkness exclude the possibility of a thermal or optically excited triplet state and, as a result, the existing model of excited triplet state P6 and P7 centers was discarded. The optical alignment process which induces the spin polarization of the ground triplet 3A state of the P6, P7 centers in SiC was interpreted to be caused by strong spin selectivity of the intersystem crossing (ISC) nonradiative transitions from an excited 3E state to a metastable singlet 1A state. The luminescence and optical absorption are caused by transitions between spin sublevels of 3A and 3E states. The analogy in properties of a divacancy in SiC and the N-V defect in diamond allows considering the divacancy in SiC as a potential defect for the single defect spectroscopy.