Option 1: Portly -> means stout or fat; this is a synonym of corpulent, not an antonym.
Option 2: Svelte -> means slender, slim, and gracefully thin; this is the opposite of corpulent.
Option 3: Replete -> means filled up or abundantly supplied; not directly opposite to corpulent in meaning.
Option 4: Ample -> means large or plentiful; this suggests abundance similar to corpulent, not opposite.
Hence, Option 2: Svelte -> Corpulent means fat or obese, while svelte describes someone who is elegantly slim and slender, making them perfect antonyms -> correct