Question

stable electron configurations are likely to contain

electrons with a clockwise spin.

unfilled s orbitals.

fewer electrons than unstable configurations.

filled energy sublevels.

Explanation:

Electron spin (clockwise or counter - clockwise) doesn't determine stability. Unfilled s - orbitals make an atom more reactive (less stable). The number of electrons alone (fewer than unstable) is not a determinant of stability. Filled energy sublevels (like a noble - gas - like configuration) lead to stability as there is no tendency to gain or lose electrons easily.

Answer:

filled energy sublevels.