MEANS known or proved to be true.The synonyms of the word 'Certain' are "sure, unavoidable, definite".From the synonym of the given word, we can say that the word 'sure' has the same meaning.The word 'sure' means true beyond any doubt. Hence, the correct answer is OPTION 3. Let's see the meaning of other given options:- WORDS MEANING indefinite not clearly expressed or defined hesitant tentative, unsure, or slow in acting or speaking doubtful feeling uncertain about something The antonyms of the word 'Certain' are "unsure, uncertain, avoidable".Example of 'Certain' in a sentence:NOTHING so certain as DEATH.