BELIEVED (सच होने की संभावना प्रतीत होती है, या विश्वास किया जा सकता है)'.The synonyms of the word 'Plausible' are believable, CREDIBLE, creditable, likely, presumptive, probable.From the synonym of the given word, we can say that the word 'Believable' is the most similar in meaning.The word 'Believable' means 'If something is believable, it seems POSSIBLE, real, or true (यदि कोई चीज विश्वसनीय है, तो यह संभव है, वास्तविक या सत्य है)'. Hence, the correct answer is option 3.Let's see the meaning of other given options:-WordsMeaningProblematicFull of problems or difficulties (समस्याओं या कठिनाइयों से भरा हुआ)CostlyExpensive, especially too expensive (महंगा, विशेष रूप से बहुत महंगा है)ProbableLikely to be true or likely to happen (सच होने या होने की संभावना)The antonyms of the word 'Plausible' are far-fetched, implausible, improbable, incredible, unbelievable, unlikely, unplausible.Example of 'Plausible' in a sentence:She could FIND no plausible explanation for its disappearance.