Option 1 -> Dubious means doubtful or questionable, which is actually opposite to plausible.
Option 2 -> Credible means believable or convincing, which is synonymous with plausible.
Option 3 -> Conducive means helpful or making something possible, not related to believability.
Option 4 -> Blatant means very obvious or conspicuous, unrelated to the meaning of plausible.
Hence, Option 2: Credible -> Both "plausible" and "credible" refer to something that appears reasonable, believable, or worthy of acceptance -> correct