Option 1: Impetuosity -> refers to acting impulsively or rashly, unrelated to talkativeness.
Option 2: Frivolity -> means lack of seriousness or being trivial, not about speech quantity.
Option 3: Taciturnity -> means being reserved in speech, quiet, and uncommunicative.
Option 4: Superfluity -> refers to excess or being superfluous, not specific to talking.
Hence, Option 3: Taciturnity -> Loquacity means being very talkative or verbose, while taciturnity means being quiet and reserved in speech, making them perfect antonyms -> correct