What does the principal quantum number (n) indicate?

The principal quantum number (n) primarily indicates the energy level of an electron in an atom, as well as the general distance of the electron from the nucleus. As n increases, the energy of the electron also increases, and it is found further from the nucleus. Each value of n corresponds to a different shell or energy level in which electrons reside, with lower values indicating levels closer to the nucleus. For instance, n=1 represents the closest energy level to the nucleus, while n=2 signifies the next level outward. Thus, B accurately reflects the relationship between the principal quantum number and the electron's distance from the nucleus, embodying the fundamental concepts of quantum mechanics regarding atomic structure.