Question

stable electron configurations are likely to contain
filled energy sublevels.
unfilled s orbitals.
electrons with a clockwise spin.
fewer electrons than unstable configurations.

Explanation:

Atoms strive for stability. Filled energy sublevels (like a full valence shell) give a stable electron configuration. Unfilled s - orbitals don't contribute to stability. Electron spin (clockwise or counter - clockwise) isn't related to overall configuration stability. And stability isn't about having fewer electrons than unstable configurations.

Answer:

Filled energy sublevels.