Answer:
D. found in regions called orbitals
Step-by-step explanation:
Orbitals are regions in the electrosphere of the atom where the probability of finding the electron, or the wave function that describes the motion of an electron, is greatest.
According to Pauli's Exclusion Principle, each electron has a maximum of two electrons. For orbitals that do not have both electrons, we say they are incomplete and that they are isolated or unpaired electrons.
In addition, when filling orbitals, ie, doing electronic distribution, this should be done according to the Hund Rule or Maximum Multiplicity Rule, which says that this filling should be done in a way that gets as many as possible. of unpaired orbitals.