(Daring : Timid) , (Beautiful : Pretty) , (Clear : Vague) , (Youth : Adult) , (Native : Alien)
Option:
Justification: In all other pairs, the two words are antonyms of each other.

(Daring : Timid) , (Beautiful : Pretty) , (Clear : Vague) , (Youth : Adult) , (Native : Alien)
Justification: In all other pairs, the two words are antonyms of each other.