Concept:Obsequious means excessively obedient and eager to please, often in a fawning or servile way. Its synonym must describe a similar willingness to submit to authority.Explanation:The word "obsequious" refers to someone who acts overly humble and flatters to gain favor. The correct option "submissive" means ready to obey or yield to others, which matches this meaning exactly. For instance, an obsequious person always agrees with the boss, just as a submissive person follows orders meekly. The other options are opposite in meaning: "defiant" means resisting authority, "aggressive" means forceful or hostile, and "proud" means having self-respect and not easily submitting. None of these share the sense of servile obedience. Therefore, among the given choices, only "submissive" is a true synonym.Answer:The correct synonym is Submissive (Option D).