Concept:An antonym is a word with the opposite meaning. 'Mature' means fully developed, grown, or responsible (परिपक्व). Its antonym is 'immature' (अपरिपक्व).Explanation:'Mature' describes someone or something fully developed in age, size, or behavior. For example: The child gave a mature answer. The direct opposite is 'immature', meaning not fully developed or lacking responsibility. Other options: 'Developed' means advanced in growth – it is similar, not opposite. 'Experienced' means skilled from practice – not opposite. 'Grown' means reached full size – close to mature, not opposite. Only 'immature' correctly contrasts with 'mature'. Thus, the antonym is 'Immature'.Answer:B. Immature