The correct answer is 'Indisputable'. In the given question 'Indisputable' is different from the rest of the words.Indisputable: true, and impossible to doubtExample: One fact is indisputable - this must never be allowed to happen again.Whereas, 'Uncertain, Dubious, and Doubtful are synonyms. Therefore, the correct answer is Option 1. ?The correct answer is 'Indisputable.' Additional InformationThe meaning of other words given in the options as follows: Uncertain: not knowing what to do or believe, or not able to decide about somethingExample: Ariana was uncertain about meeting him.Dubious: thought not to be completely true or not able to be trustedExample: These claims are dubious and not scientifically proven.Doubtful: If you are doubtful about something, you are uncertain about itExample: The teacher is doubtful about having parents working as classroom assistants.