Option 1 -> Obsequiousness means excessive eagerness to please or obey; this is a synonym of servility, not an antonym.
Option 2 -> Flippancy means lack of seriousness or disrespectful levity; unrelated to the concept of servility.
Option 3 -> Ingratiation means attempting to gain favor through flattery; this is similar to servility, not opposite.
Option 4 -> Liberty means freedom and independence from control or oppression; directly opposite to servility.
Hence, Option 4: Liberty -> Servility implies submissiveness and slavish behavior, while liberty represents freedom and independence from such control, making them perfect antonyms -> correct