What effect did Marcus Aurelius's actions have on the strength and skill of the Roman army?

Officers in the army now achieved promotion based on their social status.
Officers in the army now organized into more permanent social rankings.
Officers in the army now achieved promotion due to their ability and merit.
Officers in the army now controlled larger legions and had more authority.

Question

What effect did Marcus Aurelius's actions have on the strength and skill of the Roman army?

 Officers in the army now achieved promotion based on their social status.
 Officers in the army now organized into more permanent social rankings.
 Officers in the army now achieved promotion due to their ability and merit.
 Officers in the army now controlled larger legions and had more authority.

mathmale · Answer

Why not look up "Marcus Aurelius army leadership skills" or something like that?  Doing Internet searches requires imaginative phrasing of your search terms.