Option 1 -> Impious means lacking reverence or respect, particularly toward religion - not related to wisdom or judgment.
Option 2 -> Repugnant means extremely distasteful or unacceptable - refers to something offensive, not to mental acuity.
Option 3 -> Imprudent means lacking wisdom, care, or good judgment - directly opposite to being sagacious (wise and discerning).
Option 4 -> Perceptive means having keen insight and understanding - this is actually similar to sagacious, not opposite.
Hence, Option 3: Imprudent -> SAGACIOUS means having sharp judgment and wisdom, while IMPRUDENT means lacking good judgment and acting rashly without considering consequences - they are direct antonyms -> correct